@jwildeboer because we are people!
As so often most of those fights are not done by people who advance any product but more or less (usually less) involved fanbois.
Just take Windows vs. Mac. None of the people advocating one over the other has any influence in either making. Both work quite fine, still the fighting doesn't stop.
It will never stop. We are human and we all try to advance what we see as desirable. It's evolutionary. Evolution is mindless. Neither beautiful nor ugly. It just is - and we're part of it.