That definition of sportsball is not complete. It's not just a term from someone who admits they don't know or care about sports, it's also someone who realizes they're all lumped together, instead of football, baseball, basketball, softball, etc.
The term "sportsball" could be used by someone who knows and cares a lot about sports but as an aggregate - such as in selling audiences to advertisers or "We hope to get a sportsball team into this economic region. It doesn't matter which type, as long as we can make money."