1) a misunderstanding of what the current mainstream practices of third wave, north american feminism are (again, I'm Canadian so some of my info may differ from the US)
2) a tendency to associate mainstream feminism with 2nd wave radical feminism of the 1960's - 1980's
3) Not seeing the work that feminist organizations are doing, like in my city with the Men's DV shelter, the Men's Resource Centre for men who have experienced childhood sexual abuse, and the Sexual Assault Crisis Program for people of all genders.
I don't really think you would have an issue with mainstream, third wave feminist theory or practice. I'm not saying that other types of more radical feminism don't exist, or that there are beliefs other feminists hold that I don't, but I'm talking about the mainstream, third wave that is pushing for degendering of language and quitting the hierarchy Olympics - because patriarchy and oppression hurt everyone.