I'm not going to spend too much time debating a tankie, but I think most of these regimes kinda by definition are not socialist given how little power the workers had. When unions are suppressed and the military and the dictatorship are essentially the same thing, how could they be socialist? Socialism requires that workers own their workplaces, that they run them. This was not the case in the soviet union nor is it the case in china today, where businesses are either organized by the state (like in the soviet union) or mixed (CCP). The state organizing businesses or whatever you want to call them would be fine if the people owned the state, but again these were/are dictatorships.

The people don't control anything at all in your so called marxist states, and so therefore they are not marxist. Centralization is not something that I'm opposed to, but what does it matter how decentralized or centralized something is if it's not also democratically owned?

I would probably call myself a marxist if tankies hadn't so thoroughly stained the term.

Edit: I am also well aware that there were unions in the soviet union, hence the name. However they had little power, and mostly could only ever push for worker safety regulations.