Ye, often the "creator", the "head" gets credited with everything a whole team come up with. Sure, picking the good and directing it to consistent whole is important but they would be nothing without people that produced that in the first place.
Interestingly, that's probably another area where a language model could be put into service. Consider, every workman with access to say GPT-6 now has an expert lawyer, MBA, secretary, manager, etc. at his beck and call. What happens when every individual can navigate the system as well as an entire team of professionals? I'm imagining headless corporations where the only humans involved are those engaged in physical interface with the world.
I think the claim that PhDs and postdocs are fungible is what enables credit to be concentrated to the PI.
In top places though, it’s often the case that trainees have an idea, get shut down by PI, trainee demonstrates project can work, then PI changes mind.
Also in science, the usual progress of a project is often PI has an idea, trainees explores the idea, finds an even better idea, PI says great now write the paper.
But I agree with you in the sense that PIs act as the “quality control” or “selection process” whereby ideas get culled and refined. And their scientific taste is non fungible.