At a top club, those sub-elite players won't win you games. They are there to "subsidise" the career of that one elite talent who WILL make it into first team football at a big club. That's the ugly truth of youth and elite development
But Top clubs do have sub-elite players in their squads, and they actually spend money on transfers to get sub-elite players. Why do that, when additional attention to the academy can save those funds?
These days the cost of sub-elite players is insanely high, and in the Premier League especially. The starting price for an unproven at the top level sub-elite player is 15m (considering how much a player of Ibe's ilk cost).
Suso is a fantastic example of a sub-elite but pushing at a good level kind of talent. If Milan was in the PL and considering how much of a regular he is and that he has 10 or more G+A in 4 of last 5 seasons, imagine how much would he cost. I think he'd be 35m in the market easy. If he was English, add another 15-20m. He'd be around 50m plus if he was proven in the PL and English. That's where we're operating now. It's not a criticism, but we did let go of him for free (also considering Suso didn't want to sign with us, and that's were the cycle comes - lack of opportunities).
If elite players can go for 70m+ in this market, sub-elite players can go for 15m to 50m easy. It's just that Top clubs are more inclined to spend that develop, because they can afford it and since they can afford it, it stops/reduces academy players from coming through. That's the cycle. If young players don't get chances at an age when coming through, the development phase gets altered and players suffer for it. Opportunities definitely play a part in the how players develop.
You could flip it and say that elite talents will get chances, but I'd say the young players who became elite did, because they got chances. There are plenty of others who have suffered in development without opportunities.