You are correct, but the squeaky wheel gets greased. Politically, people left, and right are happy to assign the loud radical behavior and beliefs to their tribe. Low hanging fruit.

Do I think that most liberals or conservatives are what the radicals would have us believe? No, like you I don't believe that. Here's the rub, they vote for politicians who pander to the radicals even though the majority has a problem with that. Why? Because most voting is against someone or thing. "I can't vote for X because [radical element]."

I often (more often every election) cast protest "no acceptable candidate" write ins. It's just a futile protest, but I think if "no acceptable candidate" was on the ballot for every political office, and if it got the most votes none of the candidates could be on a ballot again it might just solve the problem of voting for the lesser evil. Kick the evils off the ballot until we get good choices.