Canary in the Coal Mine Part II: Promotions out of Training

I had a friend who suggested that training groups were career dead-ends. The cases of professionals for whom success at a high level in a training unit led to a position at an even higher level in the organization outside of training were few and far between.

If that is true, that is very frightening indeed. But if that is a false perception, it is also dangerous. Can readers comment on this, either agreeing or disagreeing with the premise, ideally with specifics as data points?