Pre-Stalin, the New Economic Policy was in place (as well as War Communism, which was its own thing). The NEP had controlled bourgeois ownership, and was there to build up the productive forces, kinda like what the PRC is doing now. Under Stalin, the NEP was considered complete, and collectivization of the economy occured. The economy had expanded worker democracy compared to the NEP as a consequence.

Further, socialism is not simply “worker democracy.” Socialism is a mode of production by which collectivized production is the principle aspect of the economy, which absolutely applies to the USSR. The state is not its own class, but an extension of the ruling class, in the USSR’s case the proletariat. Marxism has always been about collectivizing property into the hands of the state until classes disappear and the state, itself more of an instrument of class oppression, dies out of itself over time. Capitalism functions entirely differently and is run directly for the profits of the few, while in the USSR the economy was run to satisfy the needs of the people as best as possible.