For the standard settings I don't ban stuff official WotC stuff, although I'm not going to auto-include UA content. I voted for 3PP and balance stuff, which is essentially the same answer. I don't care if it's 3PP unless it looks OP, at which point I'll probably nix it.
All the above said, if I were running my own homebrew setting that was, say, low magic, or Steam Punk, or whatever, I'd have no problem restricting access to classes from any source to what I thought fit my setting.
All the above said, if I were running my own homebrew setting that was, say, low magic, or Steam Punk, or whatever, I'd have no problem restricting access to classes from any source to what I thought fit my setting.