Edit responding to your edit: I 100% agree that any extreme is bad. A society with no restrictions would be anarchy (note mores and peer pressure are means of restriction). But in a democratic society, anti-democratic ideas must be resisted. Once the structures of power are changed, it’s almost impossible to reverse. Therefore, I believe it is imperative to call out these ideas for what they are.
Also I disagree that progressives fall in the same bucket as leftists. All leftists are authoritarian leaning but progressives can be liberal or authoritarian.
I don’t think it’s usefully either to endlessly categorize political movements. If you are partial to post-modern thought, you could say categorizing things is a way of exerting power of them. This has clearly been the runbook historically of dismantling the left in America. This is mostly self afflicted due to the tendency of the left to over intellectualize things, but there has been a conscious effort by provocateurs to infiltrate left wing groups and cause discord.