So the U.S. won, tied, lost, and advanced? I will never make fun of American football again.
If you'd ask me (and I know no-one did), in every tournament it is important to score as much points as you can all the time, while your opponent(s) don't. However, if more than one team has to same score at the end of the pool and only one of them is allowed to advance, then the team that has been able to score the most in all of the previous tournament games will be allowed to continue.
Not nearly as convoluted a rule set than what American Football subjects you to. And if that doesn't make sense...then you should wonder why American Football is only popular in the US. And it is not that Europe didn't try to start a American Football League. It is just that tickets were expensive, teams have way too much low-profile players to "connect" and so, so many rules...that it became a drag to sit through a game and that can only last so long.
To me it appears that American Football is much more about destroying the opponent mentally and physically (preferably both), not about two groups of talented players that want to have a good/great game. And with the easy accessible game of soccer (in comparison) I think it isn't weird that soccer is played by much more people globally. And for those outside the US that are into full contact team sports, there is rugby.
Not to dis the players or the sport, American Football sure requires skill, stamina and perseverance. It is just not sufficiently "dressed" to appeal to anywhere else than the US.
Then again, what do I know, I ain't a big sports fan. The only exceptions are Formula 1 + MotoGP + world cup soccer.