It's just that traditionally some games were never released for the PC
LOOKING AT YOU MICROSOFT; HALO. When it states PC, it's just very clear that it is intended to be played with a keyboard and mouse as input devices.
Personally I would never be interested in a console only title for the controls handicap I'd using a controller. Controls are for platformers only.
People play Cities Skylines and Stellaris on console and I just cannot fathom how you do it, I'm addicted to that mouse and keyboard for those types of games.