A lot of people don't understand that there is a difference between liberal and leftist which makes them automatically assume that anyone speaking negatively of liberals must be a conservative. A consequence of Americans calling their centre right party "the left".
I think there's an even more pernicious problem, a lot of people understand the difference between liberal and left in theory, but they think of themselves as being leftist. They also think they are, right hand to God, as left as it gets, and anyone to their left is actually an authoritarian. This leads to these people becoming contrarians against everything actual leftists are saying or trying to accomplish in the real world, because they are the true arbiters of everything that is good and moral, and they don't think of it that way, therefore everyone else is a fascist.
For a political movement to actively despise "authoritarianism" is just stating from the start that you're allergic to wielding power. But the problem is that western left has a dogmatic aversion to wielding power.