> Let's say hypothetically that the Russian government has a Cyber Defense arm that has nearly the scope and capability as the US (the DNC/Hillary stuff seems to indicate this). Let's say this is true for many world powers (US, UK, China, and Russia for starters).
Do we think that, though? We've heard a LOT about Russia's cyber capability lately and the consensus seems to be that they employ groups of criminal kids who are by and large given free reign and occasionally called upon to look at targets of interest. We also know that the US's military spending (known budget) is something like 6x Russia's military spending, and we can imagine that intelligence spending is a similar multiple higher.
I should also make the point that the DNC/Hillary stuff is not a foregone conclusion that it was Russian. These leaks cast new light on the DNI's Grizzly Steppe paper where the NSA gave a 50/50 level of confidence that Russia was involved (but CIA and FBI said that it was greater than 50%). This leak includes information about a project called "UMBRAGE" which is a CIA project to catalog and strategically make use of hacking tools of other countries for certain projects in order to point the finger.
We do know that GCHQ has capabilities that are similar in some ways to CIA/NSA, but is it a foregone conclusion that all world powers have cyber programs this extensive? I don't think that it is.