I think a lot of families are also optimizing for university admissions. Strong athletes often have an easier time with admissions (assuming they're also good academically).

I remember having an interview with an engineering professor from Tufts when I was applying to schools, and one of the first things he asked me was what team sports I played. Being a typical nerdy kid I avoided athletics -- even though I was good at them -- and was surprised that he was so adamant about team sports. I didn't even take gym class after 9th grade because I figured out how to get an exemption, which, looking back at it, probably made my college applications weaker.

This was in 2001, and I can only imagine it's gotten worse.