This would not solve all of the new player problems including the biggest, lack of communication. It would solve the SECOND biggest problem of new players not being the right class ( I would not consider trollers, or them just not being any good, the second biggest problem).
There is a situation where a new player might be a great one but he or she didn't know you shouldn't have 2 gunners and then is stuck with the choice of being chewed out by the crew or leaving the game. That is not a good first experience.