Usually closed as non-constructive (I think that's S.O.'s wording).

Isn't that a UI problem? Punish people who do noise answers and bad edits, and see to it that garbage isn't featured prominently. Closing pages down is a desperate, blunt measure and in the long run it decays the value of your content instead of protecting it.

If it's gotten so bad that this is preventing legitimate edits and answers from improving your content, you have a very serious problem - both culturally and technologically.