I think you're on to something here, but my (admittedly anecdotal) experience (in person, not online) is that these people are not generally considered extremist. You make a very good point in your last sentence: this extremist view is held by a lot of people who are otherwise non-extremist, and it's hard for most people to differentiate between "extremist views" and "extremist people". So it ends up being considered much less extremist than it should be, which also means it gets much more mainstream acceptance than it should.