It's his view that the alt right didn't come out of nowhere. Instead, the low-friction communication of the Internet allowed these formerly scattered, always-falling-apart groups to connect and recruit in ways that were previously impossible.
I also don't think it's a coincidence that the rise of the alt-right happened when social media companies in some sense took friction negative. In the world of websites and blogs, you at least had to actively seek the next site, the next writer, the next article. It wasn't much work, but it was at least a little.
Youtube, Facebook, and Twitter were eager to give you an endless stream of content, so as to maximize User Active Minutes metrics. So their algorithms would pull up anything that they thought you'd be interested in. The theory being that any engagement must be good, which implies that total obsession would be best.
In retrospect, that theory seems to have some flaws.