Though publishers often use the difference between PC and console as the excuse for not implementing cross-platform play in competitive shooters, that isn’t even the real divide.
The divide is the controller choice, which has only eroded over the years. Over the years, various consoles have had the option to support keyboard and mouse. Meanwhile, the number of people on PC that use gamepads (even for an FPS) has increased.
And that’s without even getting into the middle-ground controller options that have appeared over the years. Some swore by the Wii’s IR wand aiming, though I only swore at it. Some swear that Splatoon’s combination of stick and tilt aiming was better than mouse control would have been. Some swore the Steam controller’s touch control emulation of a mouse gave you “mouse-like” aiming while keeping the rest of a gamepad’s feel and functionality.