The period at the end of the Soviet Union (roughly Brezhnev to Gorbechov) is often called the period of stagnation. Soviet leaders in that period were aged and in some cases so senile that they could not do much at all. Considering much of recent US history and the old folks lined up to lead this country it is hard not to to draw comparisons.
That's what happens in a system which values seniority over ability.