This is whataboutism. The Sovient Union does not represent all left-wing thought. Politics are more complicated than "left" and "right", and thus all manner of ideologies exist on the left. You could argue that many far-left people and organizations display extremist tendencies, but that is true of the far-right as well, and is not the topic of discussion.
> Are you familiar with Libertarianism? Conservatism is not the only right-wing ideology.
I am obviously familiar with libertarianism. You're implying that it is a right-wing ideology, which is incorrect. The umbrella of libertarianism contains both left and right wing political philosophies. You can be libertarian and anti-fascist, anti-authoritarian. You can also be libertarian and think you don't support fascism, even though it supports you.
In most of Europe, libertarianism manifests as a left-wing ideology. The idea that it is fundamentally a right-wing ideology is a distinctly American perspective.
https://en.wikipedia.org/wiki/Left-libertarianism
https://en.wikipedia.org/wiki/Right-libertarianism