Sales have different meanings to different user bases. Selling 5 million copies on PC is less impressive than selling 5 million copies of a game on the switch which is less impressive than 5 million copies of a game on Playstation Which is less impressive than selling 5 million copies of a game on Xbox. Fanboys manipulate these numbers
Switch doesn't do well in the multiplat arena, so you only have exclusives and Nintendo dominates that arena so the sales is bloated in their favor hence why Mario, Zelda, Wii sports is the Highest selling game of all time I believe...
Sony has the largest userbase, potential buyers, Sony exclusives sell 2mil regardless because of that, Game could be trash and it'll do 2mil eventually (price cuts/fanboy hype/etc) because I tell ya Killzone shadow fall sure did elicit responses that one would deem downright evil the way fanboyism has nikkaz lying to themselves let alone you or me. Don't believe me
The Official Killzone: Shadow Fall Thread
Xbox, smallest userbase this gen by far, still selling games at a comparable clip as the competition given the pool it has to fish from. PUBG did 2mil in 48hrs too
but the fans will say all of this is lies
PC is like Nintendo and Sony almost because they have niche gaming audiences and the userbase. That's why weird games like Dota so well. But a game like Madden won't have online play. Clearly the jocks are not gaming on keyboards. /rant