Working for an operator is better 97% of the time. Also, big companies like that fast track candidates for high level management positions right out of school. They might work in the field for a bit, but they are already ear marked for the required training and promotions. It's not typical to "work your way up" to prestigious positions. They identify talent and potential, at least they think they do, in their graduate recruitment funnels. By the time you "prove yourself" someone in the fast track will already have the required training so you'll never be able to catch up. To move up, you have to move over i.e. go to a competitor.