That is questionable. If I were a president, I wouldn't rely that much (only) on La Masia.
It's a philosophy and a choice. It's not only relying on youth but if you invest in them they need to get chances.
I agree, the problem is that Barcelona wants to win everything so players often don't have the time to grow/evolve/develop.
The real question should be what to expect from La Masia.
Winning the CL every 2 years with only la Masia? that's bullshit.
La Masia being the framework of the first team with some bought elite players? 50% La masia, 50% bought and trying to win titles? that should be realistic if you don't expect 15 titles in 4 years.
Bartra, Montoya, Sergi aren't the new Busquets and iniesta but if you handle them well they will be valuable, good and decent team members. Guys who are happy, homegrown, cheap, reliable,...
some of them (now and future) might develop world class, some will be good enough and others won't.
But only training or only play them as a desperate measure (Bartra against Bayern) is the wrong way. In that case you risk them running away and you are arguing about buying Vertonghen and co (who aren't better than the homegrown kids)
Tata eg used nobody and that's a huge mistake.
just as Valdes said, he needed Van Gaal to get his chance.
Same goes for all the others, they all got their first team chance under the dutch coaches (Gaal, Rijkaard).
Gaal and Rijkaard used a lot more youth players (remember a few games) and 95% of them are all long forgotten.
With another coach, one like Tata, none of them would have gotten a fair chance and maybe we wouldn't be talking about this golden generation.
but that's something you only know afterwards.