In case you didn't notice, only Sergi Roberto has been a true La Masia graduate that made it to 1st team in past 10 years. And during that time we have been deploying youngster promotion more than loans.
To say it is working for 30 years is flat out wrong, it stopped working long time ago since the standards of the club in terms of trophies has changed and the bar was raised
Since Abidal took over we have loaned 3 players, 2 1st team player that worked well for us and Cucurulla that is also doing well for his development.
Puig talent can very much be questioned, his level of talent in comparison to FDJ/Arthur & Alena is very questionable to say at least. To say the coach can easily give him 10 or 15 games is a very subjective assumption too
In your ideal situation, FDJ & Alena will take the Rakitic minutes while Puig will struggle to get minutes while fans curse the coach who doesn't play the favorite prospect as usual, which happened with every coach we had since Rijkaard
It stopped working because we got a new board (in 2010) that stopped following the Cruyff model and because not every generation is as talented as the 1987 generation.
Your example of Roberto is not a sound one as during the past 10 years our squad has been STACKED (more than any other club in the world) with more local youth graduates so obviously it would be impossible to continue in the same vain. A squad can only be soo big.
Besides the fantasy notion (that some have) of every generation spitting first team players out is also rather unrealistic and foolish.
As for Roberto being the only one. That is not true. Bartra became a reliable 3rd or 4rd option in a stacked defense. Left because he was too good for such a role and due to wanting continuous playing time. Rafinha would have succeeded as well (you could argue that he already did to an extend) if not for his incredibly bad luck with injuries. As would Grimaldo that Lucho foolishly sold. Munir (initially, although I was never a fan) did a more than good enough job in the current KPB role during the 2014-15 season and 2015-16 season. Much better than KPB can dream about doing. As did Sandro in his first season btw. Obviously they had no chance of succeeding with MSN around (arguably the best offensive trio in recent history, stats confirm this as well). I also recall a certain Montoya.
There have actually been quite a few youth products that have done decently given their role and circumstances.
So the notion of Roberto being somehow the only bright light (just because he is still here) is inaccurate.
No, it is not wrong at all. The model of giving talented youth chances early for the first team has been working generally in the past 30 years since the Cruyff model was adopted and it looks to have returned with the emergence of Aleñá and Puig.
Obviously it has become harder for talents EVERYWHERE to establish themselves as first team players (let alone starters) nowadays due to all the money floating around and the club's approach having changed in terms of the transfer policy.
How many times have you watched Puig for you to say such a thing? I rate him as the bigger talent than Aleñá as do many others that are familiar with both so I beg to differ.
No sane person will curse any coach for not giving Puig more than those games/minutes that I talked about (given his age and that possibly being his first season as a first teamer) with a midfield that we are currently having (one of our strongest positions in many years).