Directors with good 20+ years careers:
Martin Scorsese, Woody Allen, Robert Altman, Ingmar Bergman, Michelangelo Antonioni, Lars von Trier, Jean-Luc Godard, Francois Truffaut, Alain Resnais, Michael Mann, Jim Jarmusch, Spike Lee, John Huston, Werner Herzog, John Ford, Clint Eastwood, Akira Kurosawa, Hayao Miyazaki, Jacques Tourneur, Sam Fuller, Wim Wenders, Jan Troell, Robert Bresson, Agnès Varda, Brian De Palma, John Waters, Steven Spielberg etc etc.
I know this is a pointless exercise (it's a matter of taste etc), and I don't wanna be all Comic Book Guy about this, but all of these guys have made great films late (20 years on) in their careers, and far from all of them delivered right out the gates. QT's statement is ludicrous.