The only metric that really matters: 
Discussion
Does it matter who controls this metric ?
Of course.
Why do you ask
Never mind
Don’t want to turn this into a post about the three big mining companies
It’s a fair argument.
My understand is that they are pools though.
So if they were to be under attack from government, small miners could just unplug from the pool and join a new one.
Am I missing something there
No you’re right, you can point your hash at a different pool anytime you want