You've missed the point. Pay attention to the phrase "in quite some time". We're not the same club we were when nearly every player you listed was signed and even so, you've got to go through your list until you get to fecking Rooney and Ronaldo to get to players who played every game they were available for.
Pogba signed as a kid for the academy and left after playing only 7 times -- Juve turned him into the player he is now.
Januzaj was another academy signing who became the bright spot in an otherwise awful season before revealing himself to be shit.
Pereira spent something like 3 or 4 years in the academy before making his way to the first team and he's still only a bit part player (and not a very good one at that).
Pique played 20 games in 4 seasons before returning to Barca.
Rossi played even less than Pique.
Regardless, all of them were signed for peanuts for the academy and don't really apply.
Phil Jones has never established himself and has played less than 20 games in 5 of his 9 seasons so far - not once playing 30 games.
Rafael was class but was signed 13 years ago, as were Anderson and Nani.
Ronaldo signed for us when Bellingham was about 2 months old and Rooney when he was in diapers, as well.
I did mention Shaw. Dalot is on the fringes of the team at best now and will likely be sold soon.
Have I (missed the point)? I see you have quite the selective criteria, so let me ask you this:
How many teenagers, who were bought for big money, have been developed into "players who played every game they were available for" by the top tier teams in the top 5 leagues? For sake of consistency, let's apply the same time span you vaguely allude to, since "quote some time".
Barcelona?
Real Madrid?
Atletico Madrid? (please don't say Joao Felix, counting a player who cost an 11-digit sum in pounds would be ridiculous)
PSG?
Bayern Munich - not sure if you want to count Kimmich, who was 20 when bought. Alaba was bought "for peanuts" in 2008 so I can't possible count him in. The only one I can think of is Alphonso Davies. Who was bought last summer. I'd say he was the complete package when he came in but hey, maybe you disagree.
Juventus?
Inter Milan?
Manchester City - Gabriel Jesus came when 20, same as Sane when he was bought.
Chelsea?
Arsenal?
Liverpool?
I struggle to understand your point. What exactly are you saying? We do not develop teenage players into mainstay top class players? If so, I'd argue that's not our prime directive.
If we are directly comparing to Dortmund, then maybe there is a point. But it's the same point one can make about Monaco or Ajax. They are a feeder club who plays the market smartly. I know that, I hope you know that. Professional footballers DEFINITELY know that. If you want to play week-in, week-out and then be sold to a better team, you go to Dortmund. If you have the confidence of a Rooney, for example, you want to go to the top team already.
Just my view anyway. Don't mean to be aggressive or offensive and I apologize if I come across as such.
Edit: I've checked Real Madrid's team and must admit a few mistakes on my end: Varane was 18 when bought from Lens and has been an undoubted success. Marcelo was 19 when brought from Fluminense. Vinicius Junior is still 19 and Marco Asensio was 19 when brought from Mallorca. Whether the last two are considered "players who played every game they were available for" is up for debate. But I definitely admit Varane and Marcelo. Real have had great success with those two teenager transfers.