I have multiple reasons. I did not like the group leader of the meetings I attended. Attending meetings or weigh-ins was a huge hassle. I actually gained 12lbs after a year of membership. So, rather than waste $40 a month on a program that isn't working for me and I'm not so enthusiastic about, I'm going to try a new method.
Maybe I'm not the kind of person who can lose weight with the whole group support thing? The most weight I ever lost was on my own (on a very unhealthy low cal diet and daily exercise). I'll track my food and exercise online and see if I can lose weight on my own.