I still do not understand how Lenin 'destroyed' any democracy. Firstly, there was no democracy in Russia in 1917-18 in anything but name. Secondly, the most democratic element that existed in Russia at that time - Soviets - were actually retained and kept existing in the Soviet Union.
I find it strange that Western tradition equates 'democracy' with 'multi-party system'. One can exist without the other. There could be a multi-party system without democracy and democracy without multi-party system.
Could Conservatives, Monarchists, Social Democrats, Mensheviks advance in the political system of the Soviet Union? And when did the Soviets actually make the real decisions? There was no democracy as the full range of political ideals were not allowed to be represented and therefore the people "demos" were not sovereign. And therefore rule by the people "demo-cracy" was not in place in the Soviet Union.
A multi-party state was in place in the Constituent Assembly, and while not perfect it was far better than the overt dictatorship of the Politburo and the Chairman.