I don't think it's just that, I expect him to be the sort of coach who wants ready-made players, and experienced players will understand what he wants more both in terms of tactics and attitude.
Chelsea (and Man City) continually have the best youth teams in England, both foreign kids and national ones. They smash teams out of sight.
Last season with U21 players (all competitions, bearing in mind England has the League Cup which absolutely no-one cares about):
Ake - 4 (1)
Loftus-Cheek - 4 (6)
Chalobah - 5 (10)
Aina - 2 (0)
Musonda - 0
Solanke - 0
I'm willing to bet during his Chelsea career that zero players from their youth team go on to become established first team players, regardless of their attitude. It's too difficult at big teams as it is, and Conte is not the type to give young players a head start like Klopp or Wenger would, he wants ready and smart players and it doesn't suit his approach.
The exception for me would be an injury crisis and somebody shining, or if an exceptional player the level of Pogba came through. Even then, very difficult...
It seems most young players now have that stupid social media attitude, so maybe he will just bypass them all