There is a long history of foreign interventions in elections being catastrophic; I recently read Herman's "1917: Lenin, Wilson, and the Birth of the New World Disorder" - and he claims that there is pretty solid evidence that Lenin was bankrolled by Germany in very impactful ways.
The real activity was on Facebook groups, viralizing anti-immigration and far-left news, controling the narritive on 4chan pol and /r/the_donald, and botted up - and downvote brigades.
It was so blatant it was visible to a non-expert on information warfare like me.
The people doing this probably got paid about as much as a paid advertisement.
https://www.theatlantic.com/politics/archive/2018/11/wikilea...
I suspect we will see more of this sort of thing as the investigation continues, but of course, the investigation isn't over yet. My point is just that it was a lot more than 4chan and facebook.