Authoritarianism doesn’t really mean much. And according to the US (through the CIA) itself, Stalin-era USSR was more democratic than appeared in western media.

https://www.cia.gov/readingroom/docs/CIA-RDP80-00810A006000360009-0.pdf

But in any case, even if that was the case, it wasn’t “authoritarian” after Stalin. Like y’know, most countries after WW2 (not just Italy and Germany btw. Or people forget Churchill and FDR, and the “war economies”? The internment camps, jailing of “political dissidents” etc. etc.).