That's it, yes. TheyThere are a very few things actual scores are used for… but they're nothing that needs scores from a design perspective, since they could instead be based on the modifier, right? The reality is that they exist only as a nod to, or (depending on how you look at it) a holdover from D&D itself.
Why? If I recall the conversation correctly, Adam and Sage felt that Dungeon World wouldn't feel enough like D&D with just the modifiers, so they were kept to help preserve the intended D&D aesthetic.
For someone like your friend who doesn't have prior experience with D&D's mechanical aesthetics it will be mostly lost on them. That's ok, and you can explain it away as a holdover and nod to the game that defined the experience Dungeon World is attempting to distill.