"Left unity" is pointless. If you have a total of 5 leftists in your country,
it doesn't matter if they all unify, they're still powerless. People
seem to have this delusion that if only Marxists and anarchists stopped
fighting, they could come together in countries like the US and take
power, but in reality, this is more likely to be the
result.
It's also completely backwards. No revolution has been carried out by
only class conscious communists. Communists have to learn how to appeal
to the masses, and the masses then have to support it. This is the
problem, the highly class conscious communists will always be in small
numbers, and will never have the numbers on their own, even if they all
unify together.
Historically, the socialists and communists that come to power are
rarely even the result of "unity", but it's always one specific section
overtakes everyone else by storm. That's because some organization
figures out a way to rally the masses, and once you get the masses on
your side, all other organizations get in line or get destroyed.
The problem is not lack of left unity, but lack of any organizations
that have figured out a way to rally the masses. Nobody has figured out
how to overcome all the anti-communist brainwashing and to have a
message that appeals. It's only been successful in colonized countries
but not in the colonizer countries.
People who act like there's some simple solution that we're just all too
stupid to see, like, "if we just all stopped fighting we'd win the
revolution!" are not appreciating just how difficult the problem is. The
reason communists have not succeeded in colonizer countries is not
because they're all missing something "so simple", but because the
problem is fucking hard, and they have a mountain to climb.