There is a market out there for people who really don't have the time, commitment, or ability to learn to dance well. They are simply sold on the experience and fantasy, and that's the market the chain studios cater to best. They focus on step and step patterns, and try to get the students feeling comfortable just moving around with other. True technique is almost never discussed, and their instructors vary from some what knowledgable to six week wonders who just finished learning what they will teach you from a video. The instructors do work really hard because they have to keep selling the fantasy which often means reminding students who haven't been in for a while that they still have lessons on the books.
The studio I'm with now has a group mainly interested in social dancing, but there is a very strong group of competive dancers. We train, travel, and compete together (and win sometimes). We don't need any selling tactics because we are all passionate about learning to dance well, and our instructors are incredibly talented. Instead of holding information back, our instructors actually feed us more information than we can handle in order to push us further. There's no threat of running out of material, because they are teaching technique and not steps which takes years. After leaving the chain, it became painfully obvious that dancing was about movement and not steps. That fact is missed at the chains.