I think it's pretty common.
I don't think it's common to take it to the extreme that my therapist did.

Why would a therapist tell you? It's not like they even mention the word transference. Sometimes, but it seems to be rare.

Talking about real life experiences don't draw the feelings out. The feelings experienced between therapist and client is part of the therapy anyway, so the client feels the need for validation or whatever from the therapist. Transfers the childhood need onto the therapist.