>Blizzard is not Google in size
It's the Google/Amazon/IBM/Apple size where you end up with endemic cross-licensing patent agreements. That's where they can't adhere to it: They have a license to a thousand patents that protects them from being sued, but they don't have the right to sublicense those same patents. (L)GPLv3 requires they sublicense any patents they have to anyone who's sued, IIRC, so since they can't, they lose the ability to distribute their software.
I'd be somewhat surprised if Blizzard were a party to such an agreement. They might be party to a "patent-troll-don't-sue-me" agreement, I guess? No idea. But if they are, depending on the terms of their agreement, someone could potentially sue them over it based on LGPLv3 terms.
I'm not planning to, so I haven't done the research, to be sure. The risk scenario that comes to mind is a stretch, but say I buy a Blizzard game with LGPLv3 code in it, which grants me the right to be protected against patent lawsuits relevant to that code, and then I ship my own game that uses the same LGPLv3 code -- and I'm sued by a patent troll over a patent that Blizzard has licensed through some agreement. Guess what? I can now demand that Blizzard protect my use of the same LGPLv3 code by sublicensing me that patent. Which they (probably) don't have the right to do. So they either pay for my license or they have to stop distributing their LGPLv3 code.
For Amazon, who distribute tons of code for people to use in AWS, and the fact that they're a much larger, more collectable company, the scenario is proportionally worse.
It's all beside the point, though: In no case is it the line-level developer making the call, it's someone in management. Not everyone can (or even wants to) work for Blizzard or equivalent.
In particular, not everyone wants to work at literally half the compensation or less just so they can have full software freedom, whatever that means. The Google/Amazon/Apple compensation can be that much better than start-ups for top developers. I didn't realize this myself until I got a job at one of them.
And I'd love to be able to use RethinkDB where ever I end up next, without having to worry about whether the company legal department has a problem with (A|L)GPLv3. It's a battle I wouldn't even bother taking on in most cases; too much work when I could use something else and get back to doing real work.