I found an account dedicated to spam posting "enlightened centrist" talking points and pundits. Their name itself is part of the advertising. They even would post the same content across multiple communities, without cross-posting. And not just political stuff, they posted the same meme about 4 times without linking them.
I know this sort of thing happened all the time on Reddit and essentially it was hopeless because of how the corporate power structure worked.
"Politics" and "News" communities seem especially "apolitical" (that is to say Neoliberal) and hands-off "free speech to the end user" about what is posted. I'll frequently see a lame article, sensationalist headline, instead of the first source or the most informative one. Or I'll see a great thread about a great news story - and someone reposts the same content the next day with better timing, and it will be weaker journalism with weaker comments - yet more people will see it. Now this doesn't constitute abuse, but it will be just as permissive of abuse of the system as Reddit was.
I've also seen threads asking about where to find good sources, how to find accurate journalism... without much great advice. It's sort of an acquired skill, but we have the potential to help people acquire it.
I haven't seen as much crap as you have. Perhaps my instance admin has already done the work for me. But I think we are vulnerable to this being the case. If the instance and community moderators are hands-off, the end user has to opt-in against misinformation.