Reddit makes money from spam accounts. Even before LLMs, they'd ban you for reporting the wrong spambots, those being the ones that pay Reddit for priority access.
The replies to the LLM post are probably LLMs themselves.
I almost never go to the main "popular" page as it is full of garbage.
But I was still enjoying my niche subreddits. But in the last year the amount of AI slop has exploded and it is getting worse every day. Reposts of things from less than a week ago. Really vague technical questions with emdashes, bullet points, and ending in "thoughts?" that generate a discussion but the OP bot never replies or has vague 1 word comments.
I know that reddit makes money from ads so more bots mean more traffic which means more ads and more money.
But it is sad watching communities because useless and die.