Yes we have heard you say so many times. You got lucky. May be followers in your area are different in this regard. From what I have described yours was one of the prominent tango communities in Europe.I was coached by advanced followers myself and I do also coach new followers and leads that are new in my community. The women who coached me back then openly said: I'm investing in you because it will pay off for me someday. It's a give and take in small communities.
I never asked any advanced follower to help me. But I have not seen follower who is more skill help less skilled leader at milongas (unless they are personal friends). It is the opposite. A less skill leader would be lucky to get a dance with advance follower.
The practica setting is different. It is institutionalized way for more skilled to help less skilled. Irrespective of the role.