Re: @AC Here's the reality... its a scam in favor of Facebook.
This is the quote from the Facebook's explanation [https://code.facebook.com/posts/112130496157735/explaining-react-s-license/] of their BSD+Patents license:
"The patent grant says that if you're going to use the software we've released under it, you lose the patent license from us if you sue us for patent infringement. "
My understanding is that "losing the patent license" means you cannot use the patented technology (here ReactJS) in your product to make profit. Yes you can use/buy another product that uses the patented license legally.
So if you sue Facebook, you has to stop using ReactJS in your products, but you may still use products from others who use it legally.
Does that make sense?