>2. Patents - Is anyone here planning on suing FACEBOOK? Who amongst us has the team of lawyers to undergo that? This is for 99.999% of people not a legitimate concern. This is an RMS concern.
First, "RMS concerns" dismissed as silly and fantastic by "practical people" have been mostly proven totally valid. His dystopian essay "The Right to Read" [0] only becomes more relevant every year.
I've had to check my Amazon account 3-4 times to see if the book a friend and I were discussing supported "borrowing" it out for a limited time. Each time I've checked, it hasn't. Circumventing Amazon's controls puts my Amazon account at risk, which is hooked to my life in a lot of significant ways (AWS anyone?).
RMS may lack social graces but he is not a dummy. If anything, calling something an "RMS concern" should only call extra attention to its importance, by indicating that there's likely an understated risk that will go unrecognized by others for years.
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Second, you never know when you'll be in the 0.001%, and that's not a position you want to find yourself in if you are. Facebook is concerned about maintaining its position as the dominant social platform. When you're on a meteoric tear, they're going to bring suit against you whether it's justified or not just to try to starve you out and get you to fold, and ideally to find some reason why an injunction should be issued forbidding your site's continued operation. This license could certainly aid in that.
Things don't have to be very common to be unacceptably risky. Most unacceptable risks are in fact quite rare; you can go years riding in a car without a seatbelt or riding a motorbike without a helmet and be no worse for the wear.
The problem is that one time, years down the road, when it does matter. When failing to do that little thing will result in permanent, massive loss and/or damage. Maybe it won't happen to you, but it's so easy not to take the risk, that it's stupid to ever do so.
If you're building a product that you hope succeeds, it's stupid to use React or other software that contains a legal poison pill like this. It may not matter most of the time, but when it does matter, it really matters. The comparative cost of using Mithril or Preact or Vue is much, much more attractive than the cost of engaging in a multi-million dollar legal controversy with one of the world's most important companies, on one of the rare occasions when it really does matter.
[0] https://www.gnu.org/philosophy/right-to-read.en.html