I'm not sure that this is the case that the article is trying to make, merely it is presenting the data set that is generated when online trends are plotted. In fact, given the way the data is plotted, I would suggest that the majority of Americans *were* influenced by MSM, vs. the alt-right media.
That we have Ocean here dismissing that out of hand because of where it comes from, and the assumption that it means something negative for his side, sort of speaks to the opinion side of the article, however. If we want to have a discussion around the validity of the opinion, we can start right there, and go through every thread in this forum where conversations cannot even begin because we can't even get past which articles we allow into the conversation, let alone discuss. This tends to point to the opinion portion of the article as well, or the conclusions of the analysis, as clearly folks on the Left are willing to consider information far further to the right than the Right is willing to consider to the left, and this difference becomes more pronounced the further to the right we go (also, predictably to the left as well, but not in the symmetrical fashion one might predict).
I would also argue that these "extremist" venues have a much more far reaching influence than you suggest, mainly because I would consider Breitbart to be one of those venues, as would anyone, regardless of political leaning, who is more interested in fact than fanaticism. Fact checking makes minced meat of that site in seconds. Yet look at the influence it has, look at the number of people who actually believe every word printed. The unconditional acceptance by the extreme right of this type of "journalism" from Breitbart makes it easy to then believe the next thing that supports similar views as it flashes across one's FB newsfeed, regardless of what basement it was conceived in. And on it goes.
The one thing this article doesn't seem to want to do is change minds. More, this is a primer on "the rest of us" can understand what's going on on the Right at the moment. My biggest concern with the state of affairs today is that we can't even talk to each other, and we need to, to fix so much of what's wrong with the world at the moment, and to do that we need to simmer things waaaay way down.
For those from the Middle to the Left, this should be a cue that simply getting into forum duels trading partisan articles is not going to lead to anything but name calling and further polarization. Here are the numbers that support that.