Objectively speaking Sony consoles sell better than any other home console on the market. There is no reason on day one for them to put their game releases on PC. It would be like Apple making the Apple Watch work on Android. The point of the Apple Watch is to get people to buy iPhones more than it is to sell units overall. The point of Sony titles is to move systems.
There was no reason not to, PC market isn't in competition with consoles
Forza 5 is proof of this, Xbox stans don't complain about all games being on PC because it doesn't effect them they play on console
console is a separate market from PC