Then why make a console at all?
Consoles are the main source of GP subscribers. Console allows easiest marketing and access to the subscription and what it offers VS checking via phone or PC. Previous gen gamers move on eventually and it’s their choice to provide cross gen support in year 1. Many people are console gamers only. Xbox One has a “taint” associated with it, next gen feels (and is) new and full of potential. 1st and 3rd party digital game sales (because not everybody will use GP and still have options to buy whenever they want).
That enough reasons?