For a kid in the 90s, a trapper keeper wasn't just a thing, it was a necessity. Unlike normal binders, the trapper keeper would trap and keep. Those two actions are key when you're a kid. I don't know if you've ever seen how a kid handles important files, but it's not well. I wouldn't trust them with your tax documents or anything. Kids (and some adults) haven't yet learned how to put their stuff away without it falling everywhere. That was the genius of the trapper keeper.
All you had to do was shove all your crap into the trapper keeper and then zip it right up. Kids don't care if their paperwork is wrinkled and messed up. Not like me, an adult who stresses out if there's one crease on my paper.