Seriously, if you believe that you can simplify human thoughts about politics with a one dimensional rule, be it straight, curved like a horseshoe or a more fancy shape, you should take it as a sign that you haven't quite spent the time required to form a proper opinion.

Ah, the horseshoe! One of the toolbag essentials of any self-respecting "critical thinker", crank, centrist, or "heterodox" illuminary. :D

Already bizarre when invoking the Soviets of all people, who were socially, outside of some avantgardists which were only tolerated as long as they were considered useful or irrelevant, extremely conservative.

But then again, to many a conservative, a leftist or progressive of any kind, is "a commie", and the difference between social democrats, different breeds of socialists, or communists for that matter, is already as lost on them as code is to a cat. Shit, according to recent trends, Hitler was akshually a leftist anyway. ;)

The same goes for contextualizing political violence; it's all the same, everywhere, all at once.

>Proponents point to a number of perceived similarities between extremes and allege that both tend to support authoritarianism or totalitarianism;

From my experience that is the case. Surprising amount of people on the far right and far left when they drift into talk of violence and disruption talk about the same acts against the same people.