I may be wrong, but I don’t think the people that edit Wikipedia are the same people that are content with half truths from LLMs and thus no longer visiting the site. So I kinda doubt it matters much.

That’s certainly true for stack overflow, but in their case the moderators were very active in getting the negative feedback loop going.

Also, Stack Overflow is a commercial website, while Wikipedia is a free (as in freedom) project. Editing Wikipedia feels like you're contributing towards "an ideal", that you're giving back something to humanity, instead of just helping somebody else getting richer.