We count every game in these kind of objective analysis, Wii Sports, Mario Kart Wii, Super Mario Bross and a bunch of others are included but you seem to get the idea. Nintendo is the best by far.
Nintendo games sell for only 2 reasons:
1) Nostalgia for the gamers of old days
2) Toddlers (nah just kidding, more like 12 year olds)
3) They have been around for a looooong time, of course their games have altogether racked up a lot of sales in all these decades.
The second is the same reason why COD sells so much. Kids are many, and their parents have to give up to their demands. Adults are more calculative when they are spending money for themselves.
That also means that COD is among the very best games by your logic.