Steelers Create Anti-Titan Towel

No, it doesn't.

World indicates there are other countries involved, or teams from other countries, which there aren't. Thus they aren't the world champs because they are not competing against the world and it is not a world competition.

I agree. It's not like Gunny goes around bragging about the Sydney Outbacks being the World Champion Kangaroo Ropers. Until the rest of the world gets good enough to challenge an American high school team at American football it really is no contest. The Steelers would just demolish an all world team at American football but that doesn't make them world champions. That just makes them better than any other team that the world could scrap together if they had the ability to put a team together.