In reality, the majority of anarchists joined the Soviets just fine. A huge number of proletarian and peasant anarchists joined the Red Army and banded together with the rest of the proletariat and peasantry. The remaining anarchists were largely petite bourgeois, bourgeois, etc, and this makes sense, as the new socialist state worked in the interests of the working classes while it continued to work against the petite bourgeoisie. In other words, socialism was liberating for most anarchists, but continued to oppress the minority of anarchists that did not gain from socialism.

The narrative of Marxists stabbing anarchists in the back is meant to split the left. Of course there’s ideological disagreements, but the idea that the anarchists were so weak and ineffective that they got rolled completely makes anarchism entirely unconvincing. The reality is that the majority of anarchists didn’t actually fight back, they fought alongside the Marxists and generally came to Marxism over anarchism. They were fantastic comrades and their victories in defeating the Whites with the rest of the Reds is erased to keep leftist infighting going.