Historically speaking Democratic and Republican movements have all revolved around ruthless suppression of opposition that didn’t fall into the bounds of what was considered acceptable Classical liberal/Republican politics.

The Socialists/Left aren’t unique in that regard. Ironically they’re probably the most honest about it. I’d imagine because the suppression of socialist and communist movements is still relatively fresh in the historical record. We forget that part of our history at our peril. Our forefathers though were rather thorough in setting about their work. So it’s a problem we never needed to really confront or be reminded of. It’s also part of why the mainstream Right-Wing today largely doesn’t consist of any of the ideologies and beliefs that were considered ‘Right-Wing’ at the time the terms Left-Wing and Right-Wing entered the Western political lexicon.

Also why our history books in schools tend to provide absolutely Black and White views regarding anything outside of the bounds of enlightenment political theory and philosophy. Instead of the nuances of reality and fuzziness of actual Historical events.