thoughts on the workers' opposition?

been reading Barbara Allen's biography of Shlyapnikov. Very well written and sourced almost entirely by archival stuff. But depressing because the workers' opposition gets run roughshod over by basically everyone in power (Lenin, Bukharin, Stalin, Trotsky, Molotov, etcetc). Been wondering what others' have read on the workers' opposition and what your takes are.

The 1930s have been by far the most depressing

But even the late 10s and early 20s have some "dude wtf" moments from leadership imo

Somewhat relatedly, what do folks think of the Democratic Centralists? I've actually never heard of that faction in the 1919-21 debates before