In my experience, some progressives are authoritarian-ish, but the same can be said of conservatives. I don't think it's a property of the political belief itself as much as some people have an innate character trait that makes them very all or nothing and probably not just about politics. Those kind of people are probably fairly intolerable to begin with, but the last few years we (both liberals and conservatives) have given a pass to people with nightmarish personalities for some reason.