NFL is the best American Football league in the world though. So might as well be World Champions. And you'd be surprised to how many people know and actively follow association football here.
But still, a sport without representation from anywhere else in the world, not even Canada, can hardly justify a title called world champions. It is like a bunch of domestic Chinese teams competing in pingpong or badminton and call the winner world champions.
At least MLB has Canadian teams, but still a huge stretch.
Yeah, I know football's popularity is growing in the US, but compared to the rest of the world where football is supreme (for the most part, with some exceptions of course), football in America is what, No. 5?
By the way, is there still NFL Europe nowadays?