Indeed, or they never knew in the first place. I think people generally overestimate the average developer's knowledge of the mechanics (not just EQ here, I would think it's applicable to almost any large rpg). I'd guess that the theorycrafters at Steel Warrior and similar sites knew far more about the game mechanics than most of the devs. There may be some devs that had all the answers (probably the initial system designers), but most of them never really touched real mechanic design/implementation and were also unlikely to have played the game at a competitive level. Even for the people who 'should' have known, there are problems where the implementation didn't match the design due to bugs or miscommunication, and all issues are compounded on long projects (all mmo's) due to turnover. Once something's in its 3rd expansion and seperated from its initial devs by at least a couple of rounds of turnover, who knows how the fuck anything works or has any clue if works how it's supposed to work.
Some things, like the dumb stats, could just be ticking the wrong dropdown or filling in the wrong row, but others, like the Mosscovered Twig or the Donals BP, just point to a fundamental misunderstanding of how the combat system works. What's worse is when things like the BP need multiple rounds of nerfs. It's one thing when a noob dev does something noob. It's another when (presumably) multiple devs looked at the problem the noob dev caused, and then came up with a solution that didn't really address the issue at all. Of course, we also shoudn't underestimate how bad decisions can creep in and compound after months or years of 100 hour weeks fueled by nothing more than Mt Dew, Doritos, and opiates.
More modern games likely have more structured content creation tools that let things be created or generated within acceptable bounds to prevent similar things. That also makes everything feel bland and worthless though, so there are ups and downs here. I sound negative about it, but In retrospect, I prefer the occasional brokenass itemization to bliz stat incrementers.