Asymmetric warfare comes in many guises.NATO has the best weapons but the cost of them is extremely prohibitive. I hope NATO are learning the lessons of the value of masses of cheap and deadly throwaway equipment.
Aside from the obvious main one of conventional vs. guerrilla war, there are economics, politics and perhaps most ultimately, resilience to a rising body-bag count.
The Russians can afford to have cheap equipment that can prove to be ineffective - as the state's tolerance for high casualties is not a new thing. Conversely, imagine if the (modern) UK had a few hundred soldiers killed because the reactive armour on the tanks was ********?
Right now the USA are in a major crisis on deciding what to do because of 3 dead soldiers. Russia wouldn't even blink at that if it suited them, or conversely are well capable of starting a war if that suited them instead.