>Other than being at the center of controversies and having a lot of public notoriety, I'm not seeing anything.

That's basically it, as far as I can tell. They're heretics that weren't sufficiently shut-up by the societal forces working against them.

I think Scott Alexander explains the phenomenon pretty well: http://slatestarcodex.com/2018/05/23/can-things-be-both-popu...