Of course there's a limit on athletic scholarships. The limit is 12.6 scholarships for men's track and field/XC. If you give each guy 0.6 of a full scholarship value, you get 21 guys. Consequently, there are 21 events in T&F.
Anyway, if you start giving guys 0.3 of a full scholarship, you get 42 guys. That's a decent team.
But wait, there's more! Academic money. Stanford is not going to recruit idiots. They'll fail out of school. Despite its overall athletic success, Stanford does not recruit your typical Prop 48 dumbass. They recruit top notch academic AND athletic kids. Add academic money in there, and you can spread those 12.6 around a lot.
Furthermore, when a place accumulates as much talent and success as a Stanford and Oregon have done, what top recruit WOULDN'T want to go there. Forget the money, I'd be a friggin walkon with that team if I thought the atmosphere, coaching, and resources would make me become all I could be as a runner.