I totally get that view and it bums me out. I can say there is reasoned debate about the different licenses as you can see in this thread. We've changed an explicit patent grant into a debated implicit one. We thought the first was clearer to folks but when debate turned into action we decided winning the debate wasn't important we should just do what would allow people to use the code. I know big companies can look opaque and self-interested on the outside so I get your view. Just sharing as someone part of the internal discussions what happened and why.
You forgot to mention that the explicit grant came with obnoxious conditions, and those conditions were the crux of the issue. Your characterization of the change says a lot about the internal discussions in which you participated.
I think it's unlikely that Facebook added the PATENTS file in order to make things easier for other companies and not for self-interest. It's an explicit patent revocation, not just grant. If I'm not mistaken, there was backlash against an earlier version of the file as well. Only later they tried to spin it as something they were doing for the public.
