I think that is partly a perception due to the internet forum being a thing that coincided with the 3e era.
You are probably right about that. I think the combination of the internet, and things like 3Es very fluid approach to multi classing (plus all its feats and other elements) played a role.
AD&D had people mechanically optimizing where they could and you could read about them in Dragon magazine and such, they were often called munchkins.
Definitely. I recall players doing what they could in 2E. Min maxing was certainly a thing. It could even occasionally present an issue, but just nothing like on the level I encountered in 3E. The biggest issue it presented in most of my campaigns wasn't so much about balance (as they only through it off so much, and if they threw it off too much, the spirit of the rules was considered much more important than the letter of the rules, so something that felt off got instantly nixed by the group (i.e. this combination was clearly not intended, it is way too powerful)...it usually presented more of a role-play issue (the player focusing more on mechanical benefit of choices rather than a character idea. And that didn't bother me that much as some players are there for the game aspect of play
AD&D had lots of room for mechanical imbalance with the bell curve of stat bonuses, different choices on stat generation, much bigger class mechanical power differences (thieves I am looking at you), specialization, spells, race options, and items. Not all were actual choices you could make, but a lot were and there were people who worked the options they had hard.
But again, these all felt fairly minimal in impact. For 2E especially, when it comes to attributes, they didn't go with the 4d6 drop the lowest method as default. It did offer like 6 different methods, and if the GM wanted to that certainly could open up the floodgates. But the default (Method I) was 3d6 straight down in order. The optional methods produced better characters but they were entirely under the decision of the GM.
I agree thieves could be quite good. Though other characters did have baselines on things like climb too in the later chapters of the book (not as good as a thief but they could still do it). What I like about the 2E thieve versus later editions is they do stand out, and they are good at things, that other characters simply aren't (but primarily non-combat things or if in combat, very specific instances of combat).
With things like races in 3E, I didn't really encounter too many issues. There were some things in the complete race books that had issues, but those were so optional we never allowed anything that felt over powered (and not allowing something that felt over powered was never really much of a problem). The times I did bump into resistance was when someone wanted to make a character like Drizzt. Again there the issue wasn't so much mechanical, but more of a flavor concern (in some campaigns a dark elf or deep gnome in the party felt a little odd for the setting). Again, definitely there were ways to game the system. And there were enough options you could do things. But it didn't reach the heights of 3E (which I think was one of 3E's strengths, you could bend that system in a lot of interesting directions). It was there to a degree, but players really had to work hard to max out the system and it just didn't lend itself to the kinds of builds you had in 3E
None of this is a knock on 3E though. My two most played editions were 3E and 2E by far. They are just very different engines that reflected very different eras of play.
I was a big fan of 3e and on getting rid of xp differentials and having an explicit goal of combat balance for each class at every level.
This very much comes down to preference. For me, balancing the game around combat wasn't really something I loved about the WOTC era of D&D. I really liked having characters that were good at other things, and maybe not that good at combat. I also loved, absolutely loved, the whole wizards start out feeble, advance slower than anyone, but become the most powerful by the end. That isn't to everyone's taste, but it is the flavor of D&D I most enjoy.
I do love 3E though. Especially because it is a system you can tinker with to get very specific campaign results (one of my favorite wuxia campaigns I ran used the 3E system and I think it worked better for what I was trying to do than many systems designed specifically for wuxia---it did involve tinkering but that is half the fun).
I also think 3E brought back some very big essentials to play that 2E lacked (especially towards the end of its run). I think bringing back the half orc, bringing the Barbarian in, bringing back the monk, bringing back the dungeon, getting back to fighting monsters more, these were all good things the game needed (one problem with 2E is it did start to get too focused on meandering RP and story to a degree that detracted from other aspects of the experience: I remember having some sessions that were just people talking in a tavern, and that was even something folks would brag about, but the older I got the less fun that kind of gaming experience was for me---I need some amount of action).
I think both systems were good, but both had weaknesses, and interestingly, I think their weakness both stemmed from their strength (which is somewhat inevitable).
