The right wing is dedicated to the class interests of the bourgeoisie, they just want to maintain the current system by ensuring division amongst the workers and preventing any and all unionisation.The left wing on the other hand is saddled with the problem of actually changing things for the majority of humanity.

The more centrist leftwingers do all right, they barely want to change anything: Labour Leader Keir Starmer has gone back on his election promises to keep the party left wing. Thanks to incredible Tory incompetence over the past decade he has a good shot at PM next election (assuming that the voter ID laws aimed at preventing people more likely to vote left wing don't get rolled out permenantly).

The social democrats who want to modify capitalism to help the poor slightly are fought tooth and nail and have insults hurled at them from every direction for any little thing. There was a study by the LSE done that showed 75% of the reporting on Jeremy Corbyn lied about him, not 50% as you might expect from some left-right divide, but 75%!

Actual communists? Enemies of the state at home and abroad, to be killed in droves whenever possible. Organise military coups to put fascists in power so they can deal with them for us.

These different groups can't work together because they all want radically different things. This sort of left unity is impossible, PBP is a social democratic group and the centrists in Social Democrats (confusing I know) would rather work with right wingers than them.