Sometimes when when people hop online and turn on the flamethrower they hit too many people by accident. On the other hand sometimes they hit far too few. I read an article yesterday talking about the issues with radical revolutionary left wing politics written from the perspective of someone who had once been an ardent adherent but now is much more moderate. The author's viewpoints these days are very similar to my own - radical leftist social policies without revolutionary or communist viewpoints. She spent time talking about all the issues she saw with her particular former brand of radical left politics, namely dogmatism, groupthink, a crusader mentality, and anti intellectualism.
The thing to remember though is that these issues aren't something especially attributable to one branch of radical left wing politics. They are present across humanity in pretty much every setting available. People gather together with others who support their viewpoints, refuse to deem other ideas worthy of consideration, feel the desperate desire to convert everyone to their way of thinking, and dismiss any theory that speaks about nuance and situation instead of unequivocally supporting their position.
It isn't a crime to want to hang around people like yourself. I don't exactly have a lot of close friends that believe in trickle down economics! However, when in a group where everyone feels the same about something it is hard to avoid the tendency to dismiss all other opinions as ridiculous and that makes it hard to break away from a way of thinking even when it is sorely mistaken. It is also very challenging for anyone to admit that they have doubts about the things their in group believes in because it will be seen as an attack on the righteousness of the group itself instead of a desire to refine and test ideas.
No matter if your group is held together by a love of pastries, communism, Tarantino movies, or Catholicism these trends are going to hold. People will want to hear that their ideas are right, that anyone who thinks otherwise is wrong, that everyone ought to think this way, and that no theory is required to see the inherent rightness of their views. When painting a particular group as problematic we really should take time to consider if the problems we see are unique to that particular group or if instead it is just that we have had more personal exposure to them.
So yes, the radical revolutionary left does have issues with dogmatism, groupthink, a crusader mentality, and anti intellectualism. Everyone else does too though so if we are going to criticize a movement let us criticize their specific beliefs rather than employing ad hominem attacks that can quite reasonably be applied to nearly every group out there.