Because there's also Greco and they have their own weight classes? Not that I would mind if the NCAA weights matched UWW Senior FS, but as it stands the NCAA weight classes are more equitably distributed along the light and middle weights (+8 lb difference between 125 - 165, +9 to 174, +10 to 184) which might be more fitting for growing college students in the 18-23ish year old age range. The UWW weights have larger gaps and are more tiered at the upper end but then again we are talking about fully grown ass men.