I have a very different experience with this approach to teaching. Before I started ballroom, I had 11 years of dance in jazz, tap, ballet, and modern. It was very easy for me to pick up new steps and technique. The first teacher I had decided that it wasn't in his best interest to teach as fast as I could learn, since it wasn't as profitable. He full well knew that my goal was competition at champ level, yet he chose to tell me, when teaching me the basics of samba- that it had no hip action!!! I knew he was wrong. I can happily say that after being with a new instructor for 2 years I am dancing at champ level and searching for a partner.
Latin Lover, I wish I could see your lessons to help you out, but you are the only one who can know whether your teacher is doing this to benefit you or to hold you back. The best thing I can recommend is to educate yourself by watching the best, and don't be afraid to ask your instructor questions.