I mean the nazis were nominally socialist. And they had heavy price and wage controls and de facto government control of much of industry. They used communism-lite.
All the NAZI leadership (after the knight of the long knives) openly spoke of their hatred of any kind of socialism -- philosophically and organizationally -- and of all socialists and socialists of all kinds were the first to be put in death camps. The entire moral and ethical framework -- the celebration of the nation and race above all else, the subservience to a singular leader, etc. reflect a hatred of socialist (internationalism, secularism, class solidarity instead of nationalism, helping the poor and weak, women's liberation) values which were considered "degenerate" and "Jewish"
(And unlike Stalinism/Maoism which also reflects similar outcomes in this case the goal is explicit and stated and propagandistically proclaimed rather than hidden under a layer of Bolshevik ideology)
So I'm not sure why libertarians etc (and recently Elon Musk) in the US keep repeating this assertion ("NAZIsm is socialism!) as some kind of fact. It only underscores a lack of knowledge of history, it's not some "gotcha", it's a self-own that only takes advantage of people who don't know the history.
First they came for the Communists...
Then they came for the Socialists...
Then they came for the trade unionists...
Then they came for the Jewsthe USSR came after all of those (who weren't Bolshevik aligned) but the Jews, they did let the jews live but they closed many of the synogogues and many of them had to flee to barely hospitable fringe regions to practice their religion.
(And frankly people who grew up in the Eastern Bloc in USSR-times were not taught this in history class, either. Or they got a distorted version of it)
What was established there in the late 20s and early 30s was very much a return of many of the forms of Tsarist autocracy, but with a paint job.
"Socialism in one country" and the efforts around it was the re-establishment of Great Russian Nationalism and a cult around a leader as the motive force of everything. Underneath that there was some usage of aspects of "Marxist" ideology, so it's not nearly as clear as what happened in Germany, but it's not dissimilar.
There's a reason why the Molotov–Ribbentrop Pact was able to be signed.
In that Marxist sense, that "socialism" has a very limited implication about a very limited set of concepts around putative public ownership of the means of production, one could call the Stalinists socialist. But by that use, then one should be aware that it's a trait of a set of ideologies that otherwise have pretty much nothing to do with each other.
And indeed, he called out the "return of many of the forms of Tsarist autocracy, but with a paint job" explicitly in describing "feudal socialism".
A later preface (by Engels, I think? I think it was one of the prefaces from after Marx death) points out that they used the word "communist" because the word socialist at the time had become largely associated with some of those ideologies that they did not want to be confused with. And of course "communism" has since become equally overloaded by ideologies so different their adherents have pretty much nothing in common.
Already before Lenin died, there was already the notion of "left" and "right" communism, as two incompatible camps that were not even single ideologies, but sets of ideologies. Hence Lenin's "'Left-Wing' Communism: An Infantile Disorder" that covered a range of "left" communist ideologies (because the Bolsheviks were considered "right" communists)
The reality is that "actually existing libertarianism" is just as or more liable to degrade into authoritarianism as it hands over blanket authority to the private market -- and, eventually, the form of the state that arises when said market goes into crisis. As we've seen in practice many times, and with the way a whole class of American "libertarians" have embraced the triumph of the will motive force behind Trumpism in the present day. (Or lined up behind Pinochet, etc. in the 70s)
Fully agree with you regarding the "fascists are just socialist" canard.
With respect to libertarianism, I like to taunt US libertarians by pointing out that the first liberatarian was Joseph Dejacque, a French anarcho-communist, who, of course, given his anarchist background, praised Proudhon for the view that property is theft - and requires state power to oppress those who reject it - but criticized Proudhon as a "moderate anarchist, liberal, but not libertarian" for not going far enough in his rejection of authority.
It tends to make a lot of them very upset.
With respect to people repeating this idiotic claim, it dates at least back to the 70's in various places, seemingly as a counter for groups on the right that wanted to create distance from the nazis.
They weren't socialist at all. It's a common talking point from modern fascist apologists (I'm not accusing you of being one—this nonsense leaks out into the popular culture and just gets picked up by accident, too) but it has zero basis in reality if you run down a list of what they did. It doesn't remotely look like what an even lightly-socialist-leaning government would do. Such claims are always supported by pointing at the name (LOL. LMFAO.), making things up, and maybe cherry-picking a couple things that seem socialist-ish if you squint really hard and don't put them in context. There's some early rhetoric about it, but zero action, that was just a cynical appeal to populism, usually accompanied with attempts to redefine socialism itself to mean not-socialism—they wanted the word, but not the meaning.
Of course there is no real communism, there is no real socialism, and there is no real fascism. Nevertheless if I'm talking to some guy on a street I'll understand what he means if talks about com-bloc eastern europe or asia, and I understood OP was referring to communist countries in the way in which the term is typically used.
There's a reason that Communists that don't follow Leninism or its derivatives tend to view the countries that call themselves “Communist” (all of which follow Leninism or one of its derivatives) as only rhetorically socialist in system and substantively state capitalist at best, as they are run by a narrow and self-perpetuating elites exploiting the working class through, among other means, control of the non-financial means of production.
Labor unions in communist countries were directly controlled by the Communist Party.
It's very much a "it started socialist but they were used and quickly purged from the party" situation.
1. Evidence for socialism:
https://en.wikipedia.org/wiki/Beefsteak_Nazi
https://en.wikipedia.org/wiki/Strasserism
https://en.wikipedia.org/wiki/Ernst_R%C3%B6hm
https://en.wikipedia.org/wiki/Sturmabteilung
2. Evidence against socialism:
https://en.wikipedia.org/wiki/Night_of_the_Long_Knives
https://en.wikipedia.org/wiki/Mefo_bills
https://en.wikipedia.org/wiki/Secret_Meeting_of_20_February_...
https://en.wikipedia.org/wiki/Industrielleneingabe
https://en.wikipedia.org/wiki/Freundeskreis_der_Wirtschaft
https://en.wikipedia.org/wiki/Private_sector_participation_i...
See for example this pamphlet:
https://research.calvin.edu/german-propaganda-archive/haken3...
Here's a large amount of reading matter to explain. Fill your boots.
https://www.reddit.com/r/AskHistorians/wiki/faq/europe/#wiki...
Not unlike the amorphous political movement plaguing America currently.