My intention of the word introductory was not to feel like training wheels. Joeri in this thread says:

>>You have to trade off developer productivity for performance when it comes to choosing frameworks. The slower the framework the more it does for you.

And in that respect, the more the framework does for a developer, the better it is probably suited a starting point for new developers. It is a badge of success that Django and Rails can be able to serve a whole spectrum of needs.