It actually doesn't. In your "dream" scenario, everyone is filtered through a particular path - it's linear as fuck. I like the concept of no-levels, but your world would be completely devoid of exploration and quickly turn into "checklist" style gameplay.
People have complained in this very thread about EQ "lacking content" or the "artificial" timeflation that levels added. In reality, EQ had a pretty decent amount of content for the number of players in the game. The larger issue with EQ was entire dungeons went almost completely unused because itemization sucked there, mobs had pain in the ass abilities that weren't worth dealing with (charm, fear, etc.), and designers just didn't talk with each other at all. Guys were responsible for their own little "sections" of the world and that was it. So, you got zones with amazing layouts and great itemization and then you got others with terrible layouts and horrible itemization.
Your example ramps that up to 11, because what it essentially does is FORCE you go go kill the Guk Lord to get X ability or Y piece of gear before you can even step foot into Old Sebilis. So, now you've potentially even eliminated SolB as a possible progression path. And the idea of, "Well, you just have to create more mobs that give that ability, hur durrrr!!" doesn't work with an indie MMO that has 10-15 dudes working on it. Because now we're back to the problem of having to generate 3-4x more zones that are all exact mirrors of each other - an even more cut/paste version of LDoN, essentially. Otherwise, you end up with the SAME problem as EQ had, where people are going to take the path of least resistance every time. Or you have to switch to a predominately instanced game - which means you've essentially created WoW, but replaced the leveling path with even more linearity.
If that's your thing, great. Some of us prefer the "do and go wherever the fuck you want..good luck!" style of MMOs.
No I chalk it up to me not really explaining it all that well, my posts are already long enough as is and some people don't have the attention span. i'm advocating for the opposite actually, the same as you. Yeah I used some generic examples of having to do specific things but that has nothing to do no levels, that was a separate issue about making everything tradeable, getting rid of nodrop shit. for the most part having a high skill req (aka AAP) is what would keep people from twinking raid/bis dungeon gear on brand new twinks (or more realistically, ebay). Having to defeat a specific mob to gain a skill to equip something or do something would probably be either raid tier stuff or epic quest related, not dungeons/experience grinding. You can have kinda generic uses though, like say there is a skill for +20% disease resist, which is helpful against all the different types of mobs in the game that use disease attacks. it can be locked behind a quest or behind a handful of thematically appropriate dungeon bosses. It isn't required to fight disease using mobs but it helps. just an example.
How you itemize and populate the game is what will determine how linear it feels. If you only create one path then there is only going to be one path, if there is only 1 lguk then yeah everyone will end up there. An example I used was paladin epic but take FBSS for example. You can have hand crafted loot that drops off specific named if you want, you just want to spread it out. So instead of it dropping off "Frenzied Ghoul" it drops off "Frenzied Ambassador." He can spawn in Lguk, or SolB, or the Hole. He has place holders in each dungeon so you can camp him if you want but you cannot monopolize the item. the dungeons are geographically isolated away from each other so that one group cannot move between all 3. He is just as likely to spawn in any of the dungeons but he can only exist one place at a time. (That is so you can control the frequency that items enter the world, and also, several expansions down the road it's easier to farm when that content isn't as populated, just check to see if he's up in each dungeon, and if he isn't just pick one and farm it)
I think you are focusing on the wrong part of what I was saying. The ideal is a group of players fighting things which are challenging enough to give a sense of accomplishment, results in the optimal progression. Some nights maybe you wanna be lazy and farm easier shit, you can, you still gain exp (less) but the gear they drop isn't much to write home about. Or maybe you get a bug up your ass and wanna live dangerously and you convince your group to go tackle some shit that you will struggle to survive. Risk vs reward, go for it. Without levels, you only have the /con system. Everything in the world exists on a scale from red, yellow, white, dark blue, and light blue. there is no green cons. This only works because player power is linear instead of exponential, which is what happens with levels. If you have 100 hp at level 1 but 5000 at lvl 50, then there is no way to make level 1 content that will ever remain relevant to level 50 players. But if you have 100 health naked and 300 health in full gear with full skills (equivalent to lvl 50, maybe 400-500 for tanks due to special skills), then you can keep that content relevant, and you can add things or adjust it at any time. Not to mention, again, every games algorithms use level, so it becomes mathematically impossible for level 1 and level 50 to interact in any meaningful way. keeping power creep small and linear opens up everything.
So think about it like this. You have original EQ, all the content that existed then. you create a character and start out in newbie zone of freeport for example. Every mob in the world /cons red to you, except moss snakes. They con white. They are a tough battle but winnable, you generally end each fight with 50% health but it can vary depending on rng, but if you get greedy and attack a 2nd one before your fully healed and get unlucky, you can die. eventually you gain enough experience for a skill up and that skill is a 2nd attack (lets pretend you're a warrior). So instead of just autoattack and swinging your rusty short sword once every 3 seconds or whatever, you can now auto attack and Power attack (made up skill) also every 3 seconds. you are doing twice the damage basically and now moss snakes /con dark blue, but goblins nearby they now /con yellow. You can either keep killing moss snakes, they're easier, or do more challenging goblins, which drop rusty armor.
Eventually you get to the point where (what would of been around level 5 or so) that you need to start grouping in order to progress as far as gear drops are concerned. Yes you can always kill the moss snakes and gain (less) exp, and eventually gain enough skills to do more challenging shit, so technically yes any class can solo and progress, but realistically most classes need to start grouping up.
Here's the major difference though. mobs don't have levels either. They have proportionally more health and deal more dmg than players, just to ensure the game is group focused, but they aren't scaling up exponentially either. They don't have a level to look up on WoWhead of allakazam. Everything is light blue to red. shit is either easy enough to solo (but still challenging) to dangerous as fuck and prolly going to die. Your group isn't lvl 45, and limited to sol B or Lguk. Your group could be gorge of king xorbb or south karana at the aviaks or sol B or rathe mtns or castle mistmore or befallen or kedge keep or wherever. Some places will be a little easier than others, some you may have to stay on your toes not to wipe, but
there isn't that huge disparity between mob difficulty that there is with levels.
Interesting points. I think you could solve some of that by making the requirements a little more generic. Instead of having to kill the Guk Lord specifically maybe they could require you to kill any boss mob of a certain tier of dungeons. Other goals could be to use a certain skill a number of times, kill a certain number of "elite" mobs, reach a specific gear level, travel a certain distance, visit a certain number of cities, etc...
I like some of Sylas' ideas, but they don't necessarily have to be fulfilled to the letter in order to accomplish the general goal he's proposing.
Yeah you could do counters (kill x # of elites) or whatever. Again i'm just talking about a framework, do with it what you will.