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

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.