People are getting increasingly segmented into their own belief systems and are un-willing to even slightly concede to differing opinions, or aren't willing to even associate with people who believe in different things.
Seems like religion is phasing out of style and political beliefs are becoming the new religion.
Given that anyone in the alt-right would likely have all three of these traits, it doesn't seem like an unfair assumption to jump to.
Trump was the alt-right candidate, his campaign was as much a repudiation of mainstream conservatism and Republicanism as anything else.
This rebranding of "fascists" and "Nazis" as right wing has been going on a long time, but when you look at what these groups of people actually did when in power their actions were all but indistinguishable from the USSR: The hardest of hard left power structures. They were both "alt left".
However conflicting it may sound, arguments against freedom of speech and freedom of expression cannot be supported in an economic of free speech / expression. This is not actually a dilemma, because fascist politics are incompatible with these freedoms; one cannot exist when the other is the norm.
And just like in any culture and community, the best way to counter fascism is not incarceration and bans but heavy investment in high quality education, on the one hand, and heavy communal shaming and stigmatization of fascist politics and policies, on the other hand.