you say Nintendo and Xbox, but their games are so high end, that they wouldnt even run on the switch. and they’d have to make compromises due to the Series S.
and we know that they dont have a good relationship with xbox.
so your logic only makes half sense.
i agree that a multiplatform approach would make them more money, if it werent for the fact that their games dont sell on xbox. they never have.
final fantasy for example, is considered to be a playstation franchise, they sell the most on that platform.
also, exclusivity isnt just given free of charge. im pretty sure Sony paid them handsomely for it. and even had help from sony for 16 to run great on ps5.