Parenti largely avoids engaging with the question of how "socialist" the USSR was in a substantive way. He skips description of what the USSR "was" for excuses about "why"
probably composed as an invective but neatly summarizes Parenti's approach. because the book isn't about establishing 'socialist credentials' of the USSR through research, it's about how propaganda and western narratives were full of shit. that's where he lives, in media criticism, and it's really the askers making the mistake of having historians try to read it as historical research.
but there is a lesson here, not everything in Blackshirts and Reds is totally up to date, and you should bring more robust literature if you're ever getting deeper in the reeds than popular media narratives