> I feel like the internet has led to an explosion of these such groups because it abstracts the "ideas" away from the "people". I suspect if most people were in a room or spent an extended amount of time around any of these self-professed, hyper-online rationalists, they would immediately disregard any theories they were able to cook up, no matter how clever or persuasively-argued they might be in their written down form.

Likely the opposite. The internet has led to people being able to see the man behind the curtain, and realize how flawed the individuals pushing these ideas are. Whereas many intellectuals from 50 years back were just as bad if not worse, but able to maintain a false aura of intelligence by cutting themselves off from the masses.