Because football, basketball and baseball don't take any knowledge to understand. Casual watchers can sit down and know whats going on easily. My last two relationships when my girlfriends were watching with me I had to teach them the rules as we watched and explain why they were the way they were. After they understood it they loved the sport. Faceoffs, restricted areas, face off dots, blue lines, red lines, goal creases, goal lines, line changes ect ect all play a role in the sport and no one would know without explinations.