Just my view, that's all: Not too sure why the floor press would put more emphasis on the pressing muscles themselves. The PR/pin positions allow the 3 major pressing phases to be worked much better, each at their max resistance load. Resulting in much more focused emphasis.
I can see how the confidence factor may enter, with the pressing, while getting full support from the floor. And a BB'er would want that steady TUT. But you can get that same effect when using the PR in any phase positions. You do not have to touch the pin's or rest the bar on them during reps (most guy's use the touch and go method). Do not have to lockout either. Probably a case of a half dozen of one and 6 of the other. And what works the best for any individual. Good Luck.