I will loosely repeat Furr since he mention this multiple times in many cases and i think he is correct: We do know that since 1956 Stalin era is being smeared by revisionists, and since 1991 capitalist Russia make this much, much worse. If those files were containing the shocking levels of depravity and crimes to prove that the anticommunist accusations are true, wouldn't people responsible for creating the black legends of Lenin, Stalin etc. actually relased that? Their politics are based on negating the past: Stalin in case of Khruschev and USSR as a whole in case of Yeltsin, why did they not do it?

And we have an example: when Stalin private correspondence was declassified, there was nothing suspicious in it, in fact, it confirmed that Stalin was honest and consistent between what he said in private and in public.