You are in a better place though - because you're not the only react user. If indeed it turns out there are some submarine react patents facebook owns, with this patent license most other users can continue to work. Without the license, facebook then has the choice to either sue everybody (kind of unlikely) or to create the situation wherein suddenly everyone knows that they're infringing but haven't yet been sued, or to retrospectively grant the license (probably losing trust).
And if you do have the license - then what? It's still a react death-knell should any submarine patent appear; no large company is every going to agree to such an assymetrical deal.
Better to at least be left in the situation where it's likely in facebook's own interest to never surface any (so restrictively licensed) patents in the first place.
> no large company is every going to agree to such an assymetrical deal.
The thing is, if you just use react for something inconsequential, and can live with the fact that you have to cease using it when you sue Facebook, then it is fine.
You shouldn't base your business on Facebook's (potential) patents, and then attack them with your own patents - but that is true with or without the patent grant.
Of course, what would be great would be 1) a finer grained, symmetrical patent grant, or 2) a bilateral agreement between your company and Facebook instead of the patent grant. If you are big enough and have patents, you can probably negotiate something like that.
> You shouldn't base your business on Facebook's (potential) patents, and then attack them with your own patents - but that is true with or without the patent grant. [...] If you are big enough and have patents, you can probably negotiate something like that.
The chilling future effect, which I believe is the primary driver of op worries, is what if you build on React and are the next Facebook? (I.e. you are growing quickly to become "big enough" but are not yet)
Old Facebook now how a lot more leverage on you at several critical moments -- either in terms of making an offer, or in the negotiations around a more reciprocal patent licensing deal, or the aforementioned infringing of your patents, or the mere threat of either if someone else makes an offer.
The entire point of ladder kicking is to build a moat to ensure that others can't grow past you in the same way you did, and this is pretty effective at that (intentionally or unintentionally).
As you said, a more reciprocal, more finely-scoped patent balance would resolve these concerns. (E.g. "if you sue Facebook over a patent involved in React...")
And if you do have the license - then what? It's still a react death-knell should any submarine patent appear; no large company is every going to agree to such an assymetrical deal.
Better to at least be left in the situation where it's likely in facebook's own interest to never surface any (so restrictively licensed) patents in the first place.