It's no coincidence that the league started to penalize physical play more when the game began to be dominated by more black players. Just like there were never rules about what players had to wear on the bench if they weren't playing (the white audience was threatened by the "thug" appearance of many young black athletes).
When Larry Bird got in someone's face or picked a fight, he isn't singled out for being a punk.
But when a black guy acts that way, he is a punk, and it is scary.
I am not saying anyone here is racist, there are a lot of legitimate reasons why fighting shouldn't be allowed (though I think the foul calling is a little much, and contact should be treated less stringently). But there is a lot of subtle racism in the way the league has developed historically, due to subconscious knee-jerk reactions by white audience members to seeing this big black people fighting.