External hostility often pushed socialist regimes toward authoritarian measures. For example, the USSR faced significant opposition from capitalist countries, which influenced its militarization and political centralization. This external pressure created a siege mentality that undermined the potential for democratic governance.

This is something that I wish more people who talked about this would acknowledge and engage with. I get it, authoritarianism isn't good. It's not like we want that. It's not the goal. But it's really easy to sit on the sidelines from a relatively cushy life in the imperial core and judge all the people out there who are dealing with the historical reality of colonialism and feudalism and the current reality of imperialism. They are actively engaged in the practical task of liberating themselves from forces, both external and internal (old power structures/privileges) that seek to violently return them to a condition of servitude. The decisions they made have to be viewed through the lens of that context.

That doesn't mean we can't discuss and criticize them, but it's worth engaging in the nuance of the history rather than out of hand dismissing their attempts as inherently illegitimate, evil, and/or misguided. What were the conditions they were operating under? What dangers did they face? Were their actions the best strategy for achieving the future they wanted? Was what they gave up too great? Did they have the capability to take a more open path? Have/had their decisions irreparably led them astray or were/are they still on the path to that eventual communist society on some time scale?

If you think they're wrong for what they did, you still have to be able to answer the question of how you protect your revolution from forces that will spy on you, sabotage your industry, fund right wing militias to terrorize people, sanction and blockade you, or even invade you? Or if you think the path wasn't even violent revolution in the first place, what is your answer to how you get to where you want to be when the power structure that would need to allow this is also invested in not allowing this? It's a bit harder to see how this is made difficult or even impossible in liberal "democracies," but it should be uncontroversial to acknowledge that some kind of force was necessary to escape from illiberal systems like Feudalism in Russia/China or from colonial regimes like in Vietnam.

The one thing I'd push back on from your comment is about the welfare states of Europe. That's not really what socialism is about. They've made life better for people in their own country, yes, but it's on the backs of those exploited in the third world. That's why communism is inherently internationalist. "Injustice anywhere is a threat to justice everywhere." You need to be able to build a movement that can work to lift everyone up with you, or at least not drag them down for your own benefit. I'd be interested to have more of a discussion on this, but that's the standpoint I'd start from.