Cuba, the PRC, USSR, etc. All had large democratization of the economy compared to the fascist slaver system under Batista, the Nationalist Kuomintang, and the brutal Tsarist regime. Centralization doesn't inherently mean democratic control, but you can't have meaningful democratic input without control, and thus democratic output.

Again, decentralized market systems naturally result in the "better" firms monopolizing and outcompeting, this isn't something that can be meaningfully fought.

AES states have by no means been perfect democratic wonderlands, of course, but they have brought large democratization with respect to the level of development of the productive forces. I highly recommend reading the essay Why do Marxists Fail to Bring the "Worker's Paradise?" It takes 20 minutes and contextualizes the benefits and struggles of AES states. Socialism is often judged through a false, idealist lens, rather than an analysis of the actual material conditions and structures.