I don't know if Facebook has done any formal studies. Here's one way to think about it: if you have a webapp and have state in JS objects that you have to synchronize with the DOM, that generally takes a fair bit of code. React provided an approach for eliminating synchronization code entirely.
My own experience and that of the many others that created webapps pre-React and then adopted it is that its model simplifies our work and removes bugs. That's why we use it. It's also why there are a bunch of other vdom libraries and Ember and Angular have both moved toward similar one-way data flow models.
There's a lot that we do day-to-day that doesn't have research to back it up. At some point, we have to try things out for ourselves to see how they work for us.
My own experience and that of the many others that created webapps pre-React and then adopted it is that its model simplifies our work and removes bugs. That's why we use it. It's also why there are a bunch of other vdom libraries and Ember and Angular have both moved toward similar one-way data flow models.
There's a lot that we do day-to-day that doesn't have research to back it up. At some point, we have to try things out for ourselves to see how they work for us.