folding@home is a protein folding[1] simulator.
> Why not just say, HELP US FIND A CURE?
Though their work helps others find a cure, they themselves are not looking for a cure. Their contribution is only to help understand these things better by simulating the proteins folding.
I'm not saying this to downplay their work, but to explain why referring to folding and not to curing makes more sense. I imagine that it may even be the case that not all their work is with the aim of helping find cures.