To the extent this is true (I think some people have no difficulty with enormous numbers of social relations while some have difficulty getting along with more than their immediate family), it explains why communism, outside of voluntary communities like kibbutzim, never work.

Eventually, people get in control of the state and only want to protect their immediate tribe.  Maybe not even them, e.g., Stalin.  The philosophy of communism almost guarantees a form of government tailor-made for a dictator to step in.  That has happened in every case of a communist revolution on a large scale.  There is, simply, no successful example of a communist state.

There is also no successful example of a purely capitalist state with no elements of socialism.

Fanatics on both sides should take note.  The lack of success of a system, when it occurs throughout all of history since the invention of an idea, should be fairly convincing evidence that the system does not work because IT DOES NOT WORK.  It is not that every single country that tried to implement it did it wrong.  It is not that some perfect messiah will come along and magically make it work in the future.  It is that it is a bad idea and DOES NOT WORK.

That said, capitalism has a better track record, and when the free market works, it works REALLY WELL.  That's pretty much why the Western world is still trucking along and the Soviet Union has ceased to exist.