You are so right. There are so many good dogs (including pits) who need rescue. Many are there through no fault of their own. And yet many rescuers refuse to acknowledge that some dogs are dangerous and should be put down.
It really frustrates me when a dog that cannot make a suitable pet (at least for most homes and thus will take forever to place) takes up time, energy and money while perfectly delightful and placeable dogs are euthanized. And really, that is what happens. No room at the inn? The dog dies because there is no place to take it in.
I’ve known several people bitten by rescues and they always say, “Oh, it was my fault.” And when I hear what they did, I always think, “No, you did a pretty normal thing, the dog was going to bite *someone*.”