They're trying to determine how well you will do in courses in college. Surely how well you did in courses in high school is relevant. It is not sexist just because some groups tend to do better than others at a certain point in time. Girls have increased their academic success because they've historically not been encouraged to do so, but in recent decades they have. Girls in high school today are like 2nd (or 3rd) generation of women in the US to have been actually broadly encouraged to do well in school and obtain professional careers. There is an issue with boys feeling hopeless about their futures, and maybe this is a factor in why they as an aggregate have done worse in school relative to girls in recent years, but the solution isn't to lower standards.