I'm fairly sure the primary reason they want PC players in with the console mix is money. The console market is fucking massive compared to the PC base. The PC base typically has more savvy gamers with a lot more options to chase as well so the minute the game experience becomes sub-optimal in terms of match making, population, mechanics, a shitty patch or whatever the PC crowd will just bail and play something else, lots of which is free. Consoles have a far more captive audience and less to choose from in terms of solid FPS titles so they get a more stable gameplay experience for longer than the PC crowd does. Piling the PC crowd in with the consoles likely extends the life of the game for the PC players, which translates to more money for the publisher in the long run.

It's hard to reconcile in terms of competitive ability though. KBM is more or less the undisputed king of controls for shooters and the only way to make consoles competitive is to introduce a very heavy level of aim assist/auto snap for headshots. Even then it's a somewhat situational advantage as PC players can pull accurate high speed quadrant checks and 180 snap shots incredibly fast compared to console players.

The shit side of it though as highlighted here is the cheaters that creep in with it. PC has cheaters while consoles typically don't. I'm sure there are outside cases in terms of console cheaters, but by and large they're just not there. Between the occasional actual cheaters and the occasional God tier PC player that might end up in match making, I could see how the console peeps would get the shits with PC players fast.