Yes, indeed, but as several other posters also suggested, I don't think that even if the Soviet had won the battle of Warsaw and then a European revolution had materialised the Soviet Union would have dominated Europe. There would have been Soviets, as in worker councils, and a Russian influence, but domination or hegemony is unlikely for the industrialised powers of Western Europe. Unless civil wars divide Germany and France so deeply that Soviet Russia is a pole of stability, in which case the Bolsheviks might have more weight. What I was essentially saying is that I don't think you can say there was a specific inherently Russian authoritarian tradition distinct from the neighbouring countries. I didn't want to start an off-topic debate, just suggest that if the Red Army goes further than Warsaw it does not necessarily have a different Russian attitude towards governance compared to the other countries. My point wasn't to seek authoritarian histories in Europe, but rather to relativise that authoritarian history in Russia through European examples. Maybe I generalised too much myself in that process...
Interesting, thank you for taking the time to detail about Germany, I think it adds a relevant contextualisation to the discussion. What I thought about the Red Army vs Weimar Germany is that Germany itself had just suffered a major defeat and that its armies neither had the capacity nor the numbers to defeat an offensive from the east combined with a second attempt at a revolution. I don't see how France would have accepted Germany rearming itself so soon or getting a right-wing revanchist and revisionist government, but you are right to point out that the Entente would want to intervene to support Germany against a Red Army offensive. Maybe that could mean allied forces go even further than the occupation of the German Rhineland in terms of military presence? Your point about the SPD is rather convincing and historically the March Action with the Communist uprising in 1921 completely failed.
Yes Germany had been defeated in 1918,but you need to keep in mind this was not a defeat like the French defeat in 1940 or the German defeat in 1945. The German army was not beaten in the field, its divisions not surrendered to the enemy, and most importantly its men and officers not in prisoner of war camps. The entirety of German military manpower was still around, demobilized, and available to be called up again.
The German army in 1920 was not a broken army, far from it. The military leaders and taken great care to retain within the official army only the best of the best of the officer and nco corps, and in the enlisted ranks, only 150% reliable men. They were the cadres for the future rearmament, and a wholly reliable (for the generals) elite force with a strong political self consciousness. Because it was a volunteer force, there were no unhappy conscripts who would defect or elect a soldier's council. They were going to be loyal to their generals, and if the house of Hohenzollern came back they would be loyal to them.
And then you had the unofficial army, the numerous freikorps. These were like the landsknecht companies of the 30 years war, people who didn't want or didn't have peace time jobs, people who wanted to be around when there was going to be a red revolution, so they could kill people. Quite a few who had accumulated a habit of brutality and violence which they thought was the embodiment of warrior spirit (and a serious hindrance for reintegration onto civilian life). They were loyal to their commanders and the official army kept close connections to them, calling on them for the dirty work that the official army should not do for political reasons, like rounding up red leaders or anyone suspected of red sympathies, and massacring them on the spot. Or, fighting the polish nationalists in Silesia, something the official army was not allowed to do but obviously was going help anyone willing to fight for the "good" German cause. Or, on 1919, actually fight the bolsheviks in the Baltic region during the troubled months of 1919. The freikorps, too, were in a way picked men. They backed the right wing extremist causes in German politics and would continue to crush left wing uprisings wherever called upon. They would also eagerly jump on a chance to be part of reclaiming of German territory in Poland.
So, yes, in a way Germany was a defeated nation - the French and British and Americans and Belgians had beaten them and forced the peace treaty on them. Virtually all the heavy weapons had been surrendered to the Entente and were now in depots in Belgium and France. But they were not that weak. Certainly not submissive. The navy had scuttled their ships at Scapa Flow in 1919 in defiance of orders to hand the ships over to the British. That was emblematic of the spirit of defiance that the German military carried in themselves throughout that time. If called upon, a large army could quickly be raised again. And it could be equipped again very quickly, with its old weapons even, if the French and Belgians found it useful to do so.
Against this, I do not think the Russian bolshevists and the German revolutionaries had much of a chance.