The Tarrasque is a flawed creature in all editions. In case of 1e/2e, it’s not immune to being stunned or being paralyzed (e.g. Hold Person), giving the party a good chance to exploit its vulnerable period. Later editions have other flaws, most of which can be fixed by giving the Tarrasque a ranged attack (similar to Godzilla, etc.)

The flaws in 3.5e actually involve power scale. There’s combinations of abilities that are incredibly powerful, resulting in characters that are pre-planned rather than organically grown - and also meant that some classes were inherently better than others. At the same time, there were feat taxes that were essential for almost any character, which would be cutting into abilities that would be normal.

However, I’d be comparing 3.5e to Basic D&D. In this case, I’d most likely prefer 3.5e, simply because it’s more flexible compared to the rigid use of Basic’s weapons, but I instead skipped past that and went to both 4e and/or Pathfinder.

I’ve seen them somewhat often in RPGs and related material. There’s those who are blind, frail, deaf, weak or lacking a skill to do something necessary. Even Basic D&D had notable penalties for rolling INT 3-5, being illiterate to start with.

NPCs in fantasy settings still have hinderances, and they’re expected. Maybe they can be neutralized by healing magic in D&D, or there may be equipment that works around them. The wrong part is shutting down the concept, as that’s contempt for the weak (technically a symptom of fascism.)