I'm not saying that this isn't happening, but at the same time it also seems to get heavily implied in threads like these that the solution is for leftists to just get onboard with two-party neoliberalist capitalism just for this next one election, just this once, we promise.
Calling on the Democratic Party to adopt left-wing policies keeps getting branded "divisive", but calling on Leftists to adopt the center-right is treated like an attempt at unification.
The people calling for party unity don't want any of the political aspects of a united Left, they just want to carry on the same policies they had before but with more people being scared into holding their noses and voting for them.