You are right about the reasons there are so many amateurs in the php world. But i disagree with the statement that they become professionals over time. If you keep doing the same wrong thing over and over you just become better at doing the same wrong thing over and over, many being just old junior developers. Add the fresh supply of amateurs entering the php job market each year and you are stuck.

There are elites among php, you may be one of them, but having interviewed hundreds believe me the quality is very very low.