I'm not entirely sure thats true. The below are some random academy players:
Wes Brown aged 19 got 1,441mins in all comps
Darren Fletcher aged 19 got 2,299mins in all comps
Jonny Evans aged 19 got 1,427mins in all comps while on loan to Sunderland (who were in the PL)
Danny Welbeck aged 19 got 1,961mins in all comps while on loan to Sunderland (who were in the PL)
Gerard Pique aged 19 got 2,039mins in all comps while on loan to Real Zaragoza (who were in La Liga)
Gisueppe Rossi aged 19 got 1,545mins in all comps while on loan to Parma (who were in Serie A)
Feel free to ask me about any others and i'll check but most of the decent young prospects at the club got a chance either at United or on loan to a top tier team. Seem to recall Cleverely went on loan to Watford aged 19 but they were in the Championship. Either way, the above youth players who were all tipped to be first team players got decent experience at Chong and Gomes' age. We could throw in players like Jones, Smalling, Rooney, Ronnie who were also purchased youth players who got plenty of minutes.
I think the difference between Sir Alex and now is that our top quality youth who weren't going to feature much in the first team were sent out on loan to decent clubs instead rather than being part of the first team squad but never involved in the actual game. Ultimately the fans might be over hyping this batch of youth players when the Management actually think they're not cut out for it. I mean either neither Chong or Gomes can displace Lingard who is so fecking ineffective in the final third then it's a worrying sign. Still early days and perhaps Ole is giving our senior players a chance before they get displaced.
I was thinking more in terms of the class of 92 tbh. Most of the players you mentioned ended up squad players at best which is hardly what we need at the moment.
Most were sent away on loan to smaller clubs with far less pressure then playing with Manchester United. Fletcher was given bits and pieces of games in a team which was way better then this one. Meanwhile I can't help thinking that Wes was mismanaged, which lead to injuries that kind of ruined his career. Same thing with Jones and Smalling.
We're asking the kids to just go into this team and basically play better then the first teamers. That's not how football works unfortunately. Even if these kids were to do that, then the risk of them picking injuries or suffering wear and tear is too high. Id rather wait for Greenwood to burst into scene next year or the year after only to remain a key player for the club till he's 34 then having to rely on him now only for him to look shit at age 32.
So I stick to what I said. Build the foundations, let the kids grow, give them time and then replace accordingly.
PS: Mismanagement is a cruel word to use which implies that it was all the manager's fault. I don't think its the case. Sometimes manager's hand are forced into taking decisions that are basically brain farts.
Take Wes for example. Wes debuted against Leeds. It was one of those Ronaldesque debuts were you knew, from day 1, that the boy is special. I mean, he literally humiliated jimmy floyd hasselbaink so much that the guy ended up seeing red. Then United sold of Stam to 'give him space'. At the time I thought it was far too early to do so. Turned out I was right as Wes started picking injuries. Guess what, years passed, and it turned out it wasn't Sir Alex's idea either. Stam basically said that the real reason why he was sold was because the club wanted cash and basically told Sir Alex to pick a top dog for them to sell. Which means it wasn't Sir Alex fault.
Things are indirectly similar with Rooney, Jones and Smalling. The club was forced to fork big money to sign them up. Because of those fees, we were forced to play them quite regularly. What was the result of that? In Jones/Smalling case it translated in injuries at the early stage of their career, which in turn hindered their development. Rooney's story was different. He was lucky to avoid that but years of playing in the EPL meant that he was finished by the time he hit 31. Ronaldo who was always wiser then the rest, knew that the only way he could protect his career, was to leave the physically demanding EPL. In fact he gradually moved to a less physically demanding league, first from the EPL to La Liga and then to the Serie A.