That's true when we are talking about /48s. There are enough /48s to hand out to everyone (and then everyone gets 65K networks to work with). In the current Global Unicast space (prefixes starting with 001) there are 2^45 /48s. Effectively unlimited number, as there are 2^33 people on earth - so everyone would get 2^12 /48s.

There are 2^21 /24s in the existing Global Unicast Space. About 2 million. A large number, to be sure. But if every entity in the world MITs size asked for a /24, we'd start burning through them pretty quickly....