This is a myth as tiresome as the 'John Obi Mikel never passes forward' nonsense. Jose Mourinho doesn't do well with young players. He doesn't try to integrate them into the first team. Jose Mourinho wins trophies with mercenaries and then the team falls apart.
Except it's clearly not true at all. Via David Swann, here's an excerpt from the European Club Association's Report on Youth Academies, published last August:
José Mourinho’s team 19+4 won the Treble
The work José Mourinho undertook at Internazionale Milano FC is highly appreciated – especially his vision of football. Mourinho supervised the work of Inter’s youth academy via regular visits, meetings and open discussion with youth coaches in order to develop new Inter players. Mourinho launched the so-called 19+4 format in the Senior A team squad. He wanted to have 19 experienced, world-class players plus four promising youngsters from the club academy. The academy is therefore responsible for developing at least four players capable of joining the Inter A team every season.
The whole thing makes for pretty fascinating reading (Inter's section starts on page 44), and it's an important reminder that we're often presented with information via short quips designed to favour retention rather than spread actual knowledge. Inter's struggles post-Mourinho had nothing to do with the Special One gutting the team or destroying their future, and there's no reason to think that he'll do so this time around.