You mean reputation systems for filtering out low quality submissions? That's why they exist. Spam filters, reddit, stack overflow, Lemmy, whatever. And people say "what about newcomers who start with no reputation" but it always seems to work out somehow.
My point was that "was this made by AI" is the wrong question. Not everything made using AI is dogshit, nor is everything made by real people always good. And you won't always be able to tell the difference at all. Rather, let's focus on the spam problem