Oh, it's always funny to laugh at America's favorite sports, isn't it?
I never got into the two most popular sports in the US - American football and baseball, but I watched a bit and had a tiny bit of the rules explained to me. I hardly remember almost anything, so I cannot actually follow it and understand it. I could learn the rules, of course, if I wanted, but I don't see the point; I hardly watch sports anymore, and when I do, somehow these two, which mostly involve people standing around, yawning, and making a move once every couple of minutes before a commercial break don't really appeal to me.
I cannot deny that both American football and baseball are very deep games with many rules and intricacies, advanced strategies etc. but somehow I find exactly these things boring. It's like this for me both in sports and in video games: I prefer things that have simple rules, and a lot of depth added by clever design of the game - easy to learn, hard to master. Many Americans seem to be the other way - at least if you judge by the popularity of the sports - they seem to be attracted to games with hundreds of tiny, very specific rules, some of which are downright unnecessary, and some of which were added to change the balance or patch some exploit introduced by a previous, equally stupid rule. This makes a very structured game, where most of the time you're thinking about what you are allowed and not allowed to do; I just don't see this as fun. I don't play D&D or RPGs for the same reason.