I think it's more a matter of what you hear and what gets noticed. Say a girl plays for a couple of hours and in that time she comes in contact with 50 different guys. If 1 or 2 of those guys acts like an ass then those are the guys she'll remember, not the other 48 who acted normal or said nothing. Those same guys might even act that way towards guys, but because they would be using generic insults towards guys instead of sexist remarks, it becomes less memorable and expected. I'm not saying that it's not an issue or that girls are playing victim or anything. Just that it's the kind of thing that tends to stand out more making it seem so common.