For example I just recently went searching for a solution to a problem, and found 3 reddit posts with what must've been solutions because there were "awesome, works great!" responses, but I'll never know what those solutions were because the user had deleted their posts.
I mean, we could all just use Signal with disappearing messages enabled I suppose, that would keep anyone from utilizing "our data"... I fear we'll just doom ourselves to asking the same questions over and over and over and over if we can't build lasting, searchable, repositories of knowledge.