Holy shit, you are caught up in the semantics and missed the point entirely.
No, I'm really not. I'm pointing out that you are looking at a very small portion of each game, without regards to the overall picture, and trying to make direct comparisons. I assure you I understand your point, because I used to share it.
Let's say you are playing limited and you keep a 2 land hand, with 5 spells that all cost 3+ mana, you have about an 80% chance to draw a 3rd land by your 3rd draw. I'm assuming any land works here and you don't need a specific color. 80% is pretty high, but that's still a 20% chance you fail to do so and start getting mana screwed.
In poker the best starting hand (AA) is only an 80/20 favorite against most hands (other than an Ax hand, where it's about an 85-90% favorite). Over time, you will win a ton with AA, but on an individual hand you still have about a 20% chance to lose in a heads up situation.
The end result is similar. That's the only part that you can compare. The individual mechanics of the different games don't translate to each other. Yea, not being able to use an ability randomly in LoL would suck, obviously. Getting mana screwed sucks, yes, obviously. But, you can't remove the mechanic and assume it improves mtg just because it removes the occasional feel bad moment. It's not a net zero situation, because someone (your opponent) benefits from that mana screw. While it removes YOU feeling tilted, it decreases the opponent's enjoyment as well. As counter-intuitive as it seems, these things increase the overall enjoyment of the game. It's just that the people benefitting from it don't realize and they don't say anything about it. When some casual scrub wins his FNM because the two best players he faced both got mana screwed/flooded against him, they don't say 'thank god for mana screw!' they are just happy they won. They might feel a little empathy for their opponent when it happens, but they don't just say 'nah, i didn't deserve to win, here you take the prize'.
Like I said above, I used to have the EXACT same opinion you do of these mechanics. Heck, I still don't
like them, I just understand they are necessary evil. When the original WoW tcg came out, I thought the base game was brilliant and tried to get friends to play it. Alternatively, I wanted to make a variant of mtg where you can play any card face down as any basic land, and just having all non-basics in your deck. Neither those ever caught on.
You can make as many logical arguments about why the mechanics suck (and I agree, individually, they do) but the results have shown that you have to have sufficient randomness or the game fails. Removing, or drastically reducing, screw/flood in mtg would move it too far into the realm of chess. Then, the best players would win 85-90% of the time (instead of the 65-70% currently) and the average player would get frustrated. There is no good way to add random effect cards, like HS, into the game to replace that loss, either. Draw and matchup RNG isn't enough, we already have them. If you can come up with some other form of randomness that fits into MTG's structure, while keeping the highest winrates around 70-75%, and eliminating mana RNG, then you would have something. But, you can't just say 'the game would be better if you simply removed mana screw' that statement is not correct and is very short sighted. It SOUNDS good, because no one enjoys when they get mana problems, but the end result would actually hurt the game.