>>Or is the problem that /r/the_donald exists? Just don't go there if you don't like it.

I think the issue with r/the_donald, and other extremist subreddits (and online communities in general) is that they generate lies, whip each other into a rage-induced frenzy over those lies and then spread that hatred elsewhere on the Internet, and some of that even spills onto real life via certain conservative news outlets. In addition, anyone who even slightly disagrees is banned with prejudice.

This makes the problem difficult to ignore.