Nothing, if it delivers what you need. Maybe the powerful side of react-smooth-dnd is animations that feels like you really moving things.
I just implemented it in a Meteor site using React for the frontend, and it worked beautifully, smoothly, and with perfect React orthodoxy. I was seriously impressed.
May be better to ask what this does better?
s/he just did ask that question.
My request was for the positive reasons to use this library, rather than the negative reasons for not using the other.