I think, like most others, there’s a difference between banning for power, and banning for story.
For power: No, that’s why we have VALUE rules.
For story: I can see doing this, although I haven’t had occasion yet. Much like everything we’ve already seen with the evil or Dragonborn sessions, it gives people the chance to experience something different. So communication ahead of time, and I thought @Darthbinks bringing the pre-gens is a nice way of helping out players who might not be able to prep.
Classes/subclasses, no. Because it doesn’t solve the problem. If someone wants to power game, they’re going to do it, I’m not going to read dozens of books to try to stop them. I think as the others described, it’s better to work with the player to achieve the right balance within the party, and if needed tone things done on an individual level with agreement from the player. So long as the party agrees with what level of strength they’re aiming for (a Tomb of Horrors party may be differently balanced than a standard one), then it’s not an issue.
I will say this: I’ve learned that a party doesn’t need to be completely balanced in combat. Maybe even “shouldn’t” be. It took me awhile to learn that as a DM. Characters are more than their damage output. Ideally, each character in a campaign has their own strength, whether it’s combat (ranged or melee), stealth, intelligence, jack-of-all-trades, or whatever. In one event, maybe the strongest combat player shines. But maybe in the next one, they have to hold the line against the big evil monster, but the actual most important thing is that rogue who has to make balance checks to get across the beam to reach the artifact. Or the high intelligence scholar who has to quickly decipher the script to banish the demon (did I just slip into Cthulu? Sorry). As long as each person in the party believes they have their own role to play, it works out.
For Story: Yes, I have, to make for a better story for players. Since it’s conveyed before players ever make characters, I’ve never really had anyone fight too hard against it. Probably because it’s done to make for a better story for the players, not for a DM’s personal amusement. Re: Krynn, if I was running that era as a campaign, I’d ask for no clerics/paladins for that purpose.