Really, an observation I've had about FOSS projects where these identity politics flourish is that the code is of pretty poor quality - sometimes I wonder to myself if they are so virulently into identity politics as a result of it.  Narcissism seems a good explanation, then - you project your fear that you are in some way a fraud upon someone else and then they are the one that has to defend it, right?  It's almost pathological in these communities - they have not developed the means to weather criticism maturely and so they have become dependent on the impeding catharsis.