The older I get the more I realize that, with capitalists holding so much power all over the world, it's extremely difficult for a socialist/communist state to exist without it being pushed to become an authoritarian state.
I can see how the absolute onslaught of pressure from those capitalist powers on all sides - propaganda, sanctions, trade wars, blockades, posturing, funding opposition parties, funding rebel groups, sabotage, proxy wars, etc. - could turn any well-intentioned leaders to paranoia and state violence.
That's not to say existing and/or historic communist/socialist states have/had pure, innocent leaders, or that I blindly give any of them a pass. It's just an extremely difficult environment in which to demonstrate the potential of such governments.