Man, I don't really know. We always thought several talents would emerge once every few years. In every decade we had a B team strong enough to compete in every tournament.
The most reasonable explanation is that we are prioritizing strength and stamina instead of technique since the youth system. Brazil is still revealing good defenders and defensive midfielders. In the Champions League final we had Marcelo, Filipe Luis, Casemiro and Danilo playing, all mainly defensive roles. But the lack of talented strikers and attacking midfielders are baffling.
The domestic league level is shit, the best managers are the ones who can make defensive and compact teams with efficient goal ratings. It's all about efficiency now, not about creativity like how it used to be.