If all companies issued code under these terms, and they all used each others' code, it would certainly make patent lawsuits impossible between them.

That might or might not be Facebook's goal in the license, but regardless, it seems like a great outcome. Likewise, avoiding that outcome might or might not be Google's reason for not using this code, but since other companies are, it seems in need of explanation.

> it would certainly make patent lawsuits impossible between them

Or they sue each other anyways and it takes another 5-10 years to figure that situation out, hobbling any OS development under those licenses while there are very clear and widely used and accepted patent grants available.

There's a reason the FSF recommends Apache 2.0 if you aren't going to go GPL.

I get that Apache and GPL are well-established (perhaps not GPL3 yet though?), and that encourages stability to use them.

But this new patent license is stronger. If it would make the industry safer from patent armageddon in the long term, it might be worth the effort to popularize yet another license.

The reason is not just that Apache is well established, it's that it's sane in its extent.

Let's say 10 years from now Facebook decides to go on the warpath over fairly bogus patents. The EFF puts the headline patent on their Most Bogus patent busting list and then puts out the cry for "who is with us?"

No company using any Facebook open source code answers.

How does that make the industry safer?

Well, let's say that Facebook is using other company's code with a similar patent grant. Then Facebook can't go on the warpath in the first place.

I understand there might be a chicken-and-egg problem here. But the final outcome seems optimal with this license. And someone has to go first.

But is there evidence that Facebook is willing to use other companies' code under similar grant?