So we both agree that the Stalinist Sovietunion and the KPD, which allied themselves with them arent left?
One country ended up with Nazis. The other ended up defeating the Nazis. I'd say the Bolsheviks did a better job, didn't they? The fact that there was oppression against Mensheviks and SRs in the context of a civil war, doesn't mean they're anticommunists, they didn't quite literally enable the Nazis in order to murder the ones who were more communist than them, but defeat them instead.
Want to find the blame for Nazism in Germany? The fault is primarily of Nazis, and then of Nazi enablers, and then of anti-communist leftists.