It is with Gran Turismo, I haven't noticed that with other games I play but then again I don't play online and I mainly play story driven games, or games like Metroidvanias, and those would be absurd if they drip fed all the content. So most games I play are complete day 1, other than adding extras in DLC. But with GT we're not talking about extras, we're just talking about the rest of the game they promised.
I guess PD feels like they can get away with it, since they've been doing it since GT6. That's fine then, I'll buy GT7 when they're finished.