Something's going on. I'm not one to dwell on phantom conspiracies, but now that the election is over, I see contrarian views posted to comment sections that I suspect are bot-derived.
For one example, I enjoy "Pilot Debrief" on YouTube. The host dissects mostly GA plane crashes and offers theories on the why and wherefore. If the pilot in question has made obvious, glaring mistakes before and during the flight, the comment section will be chock full of criticism towards that pilot, but occasionally you get a "he seemed like a really cool guy" thrown in. One sentence, just like that. Just trolling, but often no follow up arguments. Like a fart in an elevator.
My theory is it's most likely done to add clicks to the algorithm, but in the above example, the owner of the channel seems pretty above-board, and unlikely to subscribe to a bot service to enhance his views and comment posts; maybe what we're noticing is a more invisible version of what we recently learned about "Honey"?
http://forum.level1techs.com/t/honey-browser-plugin-scam/222717
It doesn't explain why it would fish out old posts on an old-man car forum but maybe that's just an artifact of the AI, like those weird hands and feet you sometimes see on AI generated photos...
Just a theory. If it's happening for evil intent it'll be far too late for me to worry about because the damage will be done.