[evgen]

A more likely explanation is that these large orgs employ real lawyers who looked at the licence and grant and who then approved the use of react because they are professional lawyers who actually understand the legalities involved, unlike 99% of the commenters in this thread.

[TimTheTinker]

I suspect the real reason is that these large companies already have large patent war chests, so any suit from FB could incite countersuits from them. They have a measure of impunity and thus their exposure to risk is much less than that of smaller companies and startups.

[Spivak]

What's not to understand? If Facebook infringes on one of your software patents your choices are to rewrite your existing React code and sue them for damages or ignore it.

Once your 'professional lawyer' agrees that the license is enforceable it's up to you to decide whether giving Facebook an effective grant of all your patents it worth it.

[abiox]

> rewrite your existing React code

my understanding is that this isn't the case - react isn't itself covered by patent, and the bsd license remains in effect.