PD did a lot more than those games. 4k tech demos for Sony to GTR HUD design and NISMO 350Z aero kit design to promo videos for a few auto manufacturers to even exclusive sim setups for some auto dealerships, among more. Some could say that was work in the auto industry but that all, while not growing the team nor outsourcing lead to mismanagement of their core business which is making GT games. GTHD was only in limited demo state, PSP didn't even have a career structure and 4 cars on track, Prologue was a moneyhatting test bed for GT5 and GT5 launched buggy, broken, with the bulk of content being bad port workleaving the game to be the most patched game in console history. Shame too because there are moments GT5 absolutely shines.
Oh and Kaz's own personal experience as a driver for Nurb24 didn't bring endurance racing the way it should have been done (no driver swaps, no multiclass racing, no damage in enduro events, etc)
I hope they got their heads on straight and focus on GT6. GT6 can be absolutely amazing and all It needs is PD's full attention.