No need for polemics. I think Del is basically right.
In general, the better the side, the harder it is for a young player to get in. Take Liverpool, in the beginning Klopp played plenty of young players but most of them didn’t quite cut it (Jordon Ibe, Brad Smith, Dom Solanke, Kevin Stewart, Ovie Ejaria etc etc). In the end Gomez and Trent are the only ones to have remained (and it took a long term injury to Clyne to give them there chance) but the likes of Brewster and Jones and Elliott will still get an opportunity to show their abilities but for any young attacker, it’s tough competing against Salah, Mane and Firmino.
Re Mourinho. You could point to Davide Santon and Balotelli at Inter. No one came through at Chelsea which is obviously memorable but that was possibly systemic. But generally there are a few players here and there. Nonetheless, Kane, Son and Lucas is a pretty strong front three, not to mention the likes of Ali, Lamela and Eriksen who are also attacking players. Compare those guys to who Connolly had to bypass at Brighton, you begin to see what a challenge it is. Can’t see Troy playing more than the odd cup game here and there at least until one of them leaves or gets a bad injury. Someone like Kyle Walker Peters has a much more obvious path to the first team.
As far as the big managers of about 3 years ago went (Guardiola, Klopp, Pochetino, Mourinho, Wenger, Conte).
Wenger was probably the best in trusting young players, then Poch and Klopp, then Guardiola, finally Conte and Mourinho. Still, with the right bit of luck, who knows what could happen...