I have the impression it's the opposite. The left is becoming more militant to contain the right leaning extremists.

Ah no buddy, I'm as far left as you can go, you got this backwards

We could do that, or we could kill fascists.

The left doesn't really have any political power under capitalist hegemony where there's economic consensus in the political and ruling class. There are many leftists but essentially no political left, and at the same time politics can no longer impact our economic arrangements, irs basically a spectacle we react to from different angles. What we have are centrist liberals both portrayed as "far left" by the right, some who ignorantly react to that with "yes, I am far left!" And those who actually have a visceral hate for capitalism have almost always been dealt with on common ground between centrist liberals and the right.