Some may see this as controversial.
Should we talk about the Stages of Enlightenment in Buddhist practice?
Plenty of teachers think that we shouldn't. That's been the standard view.
The situation has for a long time been teachers holding certain teachings back until they feel a student is ready. I think that in the old world, when it was hard for information to spread, that probably worked pretty well. But we live in a different world now. Information is everywhere and it will spread whether we like it or not...