I think the problem of left unity is a symptom capitalism. Models of anarchism, communism, and socialism have wildly differing systems of social relations, organizing, governance, economics, etc. Even the sub-models in each of these categories have vast differences. But in our political discourse they're all compressed into the same box of the "left", because our prevailing system so dominates the narrative that these other systems are all erroneously viewed through a lens that presumes private property and redistribution of wealth vs no redistribution of wealth as the dividing line. Nevermind the hypocrisy of "redistribution of wealth," as corporations are speedrunning to unjustly pump virtually all forms of wealth into their coffers.
I remember when I was young and dumb and finding myself fascinated by the Venus Project and Zeitgeist Movement. The basic idea seemed so elegant and promising to me: we can use technology to solve our problems, to use technological progress to obsolete scarcity itself!. I tried to chat with people about it, and on more than one occasion somebody would just shut the conversation down with, "But that's socialism." That was the first time I realized something was very broken in our discourse, because it was like, yeah kind of technically, but it's also something very different from what we normally think of what socialism is.
That's kind of what a lot of these labels are, ultimately. Thought stopping cliches.
