It seems you have two questions. What makes sports thrive over others in certain countries, and why is important to advertising?
Well the first part is culture of the country. Soccer is huge across Europe and South America. Sure there's handball, or if you are Canadian.... Curling for instance. But those sports just don't interest people in that they just don't garner universal appeal. Why American football isn't embraced like soccer over in Europe, and Soccer struggles in Amercia I do not know other than culture and my next point. The other part to a sport's success is youth participation. Baseball is America's past time because it has been played by kids in playgrounds and Little League fields for over 100 years now. Only a extremely small percentage of those kids will ever play in college or professionally. But the ones who do play or watch, develop the love for the game that drives tickets sales, merchandising, and the watching of broadcast games. Even MLB has found it has a vested interest in promoting little league. Why sports is vital advertising has nothing to do with sports. Advertising is all about selling people something and making money. The best way to sell anyone your product is to get them emotionally invested in your product or service. To do that, you need to find an audience that's into what you are selling. Sports is a genre that has extremely wide mass appeal. So adverisers use that audience to sell them their wares. Most advertisers could careless who's going to win the Super Bowl. What they care about is it's the one game in the NFL EVERYONE watches, and that just one more... Or a couple million chances to get people to buy their product.