Recently started and it’s incredibly insightful, even just for more in-depth historical context around movements of the time period. Also chuckled that the intro mentions a couple times social-democracy being the “left-wing of the bourgeoisie/fascism” 
Yeah I was confused by reading that it was embraced since it comes off at face as anti-proletariat. I’d never heard of Shliapnikov, but from a brief scan of his writing (Theses to the Ninth Party Congress “On the relations between the Russian Communist Party, the soviets, and production unions.”), seems more in line with what I’d expect from labor that’s done labor.