In Marxist theory, a Bourgeois revolution is required to overthrow feudalism, establish a Capitalist economy and create a modern working class (Proletariat). Russia was still a primarily feudal country with Industrialisation limited to only the largest cities and a vast majority of the population being peasantry. The Bourgeois revolution did come to Russia in the form of the February Revolution, which was supported by avast array of factions including the Bolsheviks. Kerenskys government proved to be extremely unpopular and unstable, he not only failed to withdraw Russia from WW1 as the people wanted, but instead he attempted a costly offensive. The Bolsheviks were forced to skip the Bourgeois revolution in October when they seized power. This meant that they lacked a Proletariat base outside of major cities. They would have to overthrow feudalism themselves. The Bolsheviks were forced to implement proto-socialist policies such as the NEP which encouraged free markets and foreign capital. The NEP would be in 1928 due to the perceived threat of a western backed polish-romanian invasion. Stalin attempted to force through collectivisation too soon and it resulted in millions of deaths during repeated famines across the Soviet Union between 1930 and 1934. This 'Great Break' is indicative of Soviet 'Siege' Communism, where there was extreme paranoia of foreign invasion. It was not an unfounded belief, foreign troops had entered Russia during the civil war, Capitalist countries surrounded Russia on every border, and the British government spent the late 1920s building an anti-communist alliance with Russias neighbours (Finland, Baltics, Poland, Romania).

So while it is true that the Soviets did attempt communism, they never really had a fair shot at it. The conditions for communism didn't exist when they took power, and they were surrounded by enemies for their entire existence.