Distributed mining is the defense against attack.
Which implies that it needs a defense. Sans that it can be brought down. Governments can ban GPUs, mining rigs etc. so the defense gets weak while they can have powerful hardware.
What does the technology have to prevent such a thing from occurring?
Bitch please, ban computer parts?
They don't need to make a PC revolution to make a 51% attack, they have lots of super-computers to make a lot of floating points operations that, if they want it today, they can make the 51% attack.