Stop saying this. Moms who let their babies cry a little to give them a chance to put themselves to sleep are not trying to stop their babies from being babies. They are trying to help their babies learn to do things that they're capable of doing themselves (self-soothing, for example). This is healthy, normal, and developmentally appropriate.
It's rude and condescending to imply that moms who do these things are doing it for selfish reasons like wanting their babies to "grow up" and "get past the baby phase." We are all trying to do what is best for our babies. You're allowed to disagree with what that is, but don't act like anyone who doesn't parent just like you do is selfish.