Stackoverflow used to be very guilty of that too, back when I was active on it and paid attention. I tried to cause a public stir to remedy the following absurd situation:

Question and Answer is top Google result due to well formulated Q, keywords, Google algo, whatever. OK, start to see interesting responses. Closed as Off Topic or Duplicate by randos.

I argued, how can it possibly be a duplicate or off topic if it's a top search result. You're rewarding overzealous types. I suggested drastically increasing the points required to mark posts like that. I doubt I influenced anything, but it was worth a shot.