People have been astroturfing on reddit for a long time, the only reason it's not a cesspool is that reddit has a hardcore anti-marketing bent in a lot of subs and they'll aggressively out shills. I expect that GPT powered reddit bots will make the shills a lot harder to identify though.

The humans on reddit are often indistinguishable from bots as well.

It has always been a cesspool for a long time though. Only fit for consuming memes, cat pics, and financially motivated stunts like when Keanu Reeves was there the other day, using the social media account of the company for his upcoming film in a few weeks.

Each subreddit is controlled by a few essentially random people that likely have personal gain as one of their motivations.

If you think you aren't being advertised to on reddit just because the spam isn't as obvious as elsewhere, think again. The advertising there is more sophisticated than bots dropping links in comments.

There was a leak a while ago showed one of the moderators of wallstreetbets that was posting fake options gains, and it still gave him a massive following which he used to sell them a newsletter or something.

There are many subreddits where there will be a link in the sidebar to a monetized website affiliated with one of the mods.

And even 10 years ago, I remember at least 1 moderator of the programming subreddit somehow always had his blog posts highly voted and ending up on the front page, while any other submissions, especially ones that might counter his claims, would end up being stuck in the "spam filter". And if you messaged to have it unblocked, they'd only respond 1 day later, which means it would never show up on the front page due to the age factor of the ranking algorithm.