I think a pretty small group of people can have a large impact online. It doesn't take many people to spam popular social media channels with memes or whatever to get them to catch on...and then they spread via shitty people being shitty. My idea of a Russian troll is a literal person shitposting witty/ironic/etc memes, maybe tossing some gas on fires or picking fights in whatever internet wars.
That can and does spread wide and influence the discourse. If a group is all getting their info from the same few sources, they troll the same and have the same stupid arguments as those few actual troll farm trolls.
I think you guys are talking about different stuff.
Edit: oh they can be of any origin, fully concur.
What you are talking about is a portion of it.
But I might suggest looking at it like Iago in Othello. Whispering in ears saying anything and everything to get people to trust them and slowly poisoning their brains with nonsense that they are most likely to fall for.
But online it is not just from one angle, they are conning people from every angle, attacking them from the left and right, defending them from those attacks by putting up shit to support the (actual) person's bullshit argument, nudging them into trusting them as being a 'friend' while setting them up to click on bullshit links that alter their data in ways that give them more and more radicalized material on their other social media feeds (which they also have access to with different accounts helping spread their influence with those people (because the mark thinks it is more 'proof)).
https://www.rollitup.org/t/change-my-mind-please.1024266/post-15668217
Then because they have near unlimited resources, all the bullshit scam websites that push their garbage propaganda 'news' (RT, OANN, the Hill, the Nation, Breitbart, Epoch Times, etc) that supports their narratives by cherry picking information that is real and true, but picked to not give information that shows them to be full of shit with quality looking websites that give them more 'credibility'.
And every link they click is recoded and everything from how long people read something, to what else they click is used to develop a stronger personality profile on those marks to help with future trolling.
https://www.rollitup.org/t/ap-cyborgs-trolls-and-bots-a-guide-to-online-misinformation.1005699/post-15310450
Imagine if you have a perfectly updated personality profile on hundreds of millions of Americans that you have down to the district that they vote from and a AI heat map telling you the people to attack that day with the end goal to nudge them to vote for the candidate of their choice or to not vote.
And if they are crazy, nudging them to do violence so that they can be used to scare other people.
This shit is evil man. And highly effective.