One other downside is that, if you’re relying on Facebook open source, the license makes it hard to claim that Facebook is infringing your patents. Facebook could use your patented designs and processes and it’s understandable you’d want to hold them responsible in court. As part of the patent grant, you’d have to stop using Facebook open source upon claiming patent infringement.This. This is the whole freaking problem.
The problem with software is that there's no real "moat" for most products. We've seen again and again that major software companies are happy to let small competitors test new solutions and products, then eat them if they're successful.
Don't want to sell? They just pop up a clone and use their market leverage to force you out.
This license just exacerbates the problem.
Facebook's license basically reads: "Hey, if you use our stuff, we'll reserve the right to eat your business if and when we like. Want to sue us for it? Well now your product doesn't exist anymore because you lost all the licenses."
