I agree that they are perfect for those activities, but they are also versatile enough to use for all sorts of events and activities!
Take this layout for example:
It's a layout about soccer, but guess what? Only one of the papers is actually a soccer paper! This layout includes paper from soccer, karate, cheerleading, competition and volleyball!
How about this one:
This one contains paper from hunting, softball, golf and karate!
What about this card:
This adorable baby card is made from papers from the soccer, cycling, football and baseball lines!
So when searching for paper to use - look beyond the originally intended use - color outside the lines!