It is not like employment or physics in which theoretically males and females can compete for the same job or classroom seat. The school predetermines how many opportunities it will offer to boys and how many it will offer to girls by deciding which sports it will offer for each sex. I emphasize that there is nothing genetic or inherent in athletic interest or benefits.
Girls can benefit as much as boys.
Girls were let into the race just 25 years ago and thus haven't even reached the first turn yet. Further, most boys have the benefit of fathers and grandfathers who played sports to teach them and work with them.