Last time I checked Glenn Greenwald was saying that Russian interference had nothing to do with results of the last election and Hillary lost because she was a bad candidate. I have no quibble with the bad candidate line, but it's pretty clear that the Russians we're actively involved trying to get Trump elected. I think some people have legitimate disagreements with Glenn.
But I just don't think its plausible that the identified Russian activities swung the election. The Russian fake news trolls were a drop in the ocean of social media/news. The russia spend on facebook was 0.05 percent of the candidates (not even going to mention the free posting by individual supporters). FB estimated that 1 out of ~20 thousand pieces of "content" it served related to the election was russian.
In order to believe they had an impact, you have to believe russia ads/fake news are almost infinitely more persuasive than other propaganda, ads, news, etc.