Socialism lacks checks and balances because it's a decentralized/distributed model of rule. Now in reality it's possible the military could exist as a pseudo "check and balance". But checks and balances do not exist as a defined construct in socialism, by being distributed it argues it doesn't need checks and balances, because it's run by the people.

Secondly checks and balances are arguably anti-socialism even, because it would introduce a backdoor/round-a-bout way of enacting rule that wasn't endorsed and driven by the people. So no, the lack of checks and balances isn't just a Soviet Union thing, it's a socialism thing, otherwise it isn't true socialism.