No, they are not. Remove the authoritarian right wing extremism and you have no "left wing extremism."
Antifa does not exist without right wing extremism. It's
a direct response to right wing extremism.
Right wing extremism is
not a response to left wing anything. It's a response to authority worshiping religion, ignorance, fear mongering, prejudice, fear of anything not conforming to the in-group, and any authority willing to give it legitimacy.
To regard white supremacy/right wing extremism as anything like a response to left wing anything, you have to have fear and hate mongers hijacking the ignorance and prejudice of people not equipped for rational reasoning and telling them "
THEY are evil and will come and take all your stuff and try to kill you, etc., etc." You have to drink the koolaid to believe the whole world outside your ingroup is out to get you.
Regardless of whatever problems may exist in "left wing" thinking, which consists of openness to new experiences and new people and new ideas, willingness to question authority and hold it accountable, etc., those problems don't even come close to those weak ass, stunted human cognitive traits that give rise to right wing extremism, religious or political.
And one thing right wing morons always forget (always!) is that people of humane values and principles, who are not scared of everyfuckingthing, who are not prejudiced against everyone outside their immediate group,
will always fight back. We fought back in WWII, the U.S. Civil War, and numerous other times and places in history.
Right wing idiots love to believe that we are cowards for not making animal brain violence Plan A in any situation, but how would they recognize someone who isn't afraid of them at all but is not willing to commit violence willy nilly? They push and push because they don't have any better grasp of boundaries than infants, and we eventually hand them their asses. Unfortunately, they usually create untold suffering and atrocity first, as our current American right wing extremists are doing their best to accomplish as we speak.
Not that you would be honest about any of this. After all, how would
you recognize anyone who doesn't think in the most stunted, black and white terms about the world around them? If you could, you'd have the humanity to stop supporting the worst of human behavior in the world.
And "antifa" means anti-fascist. Come on. That's a pretty desperate reach there.