I don't believe there's a mass consensus that it's an authoritarian regime. I'm not even sure there's a mass consensus that it's heading in that direction, regardless of what I personally believe.
There was never a mass consensus in the USSR that it was authoritarian, because it was not permitted.
When I say not permitted, I do not mean that they had people with guns going "THINK THIS!", but that social pressure and group-think were utilised to ensure that nobody broke ranks - just like media control in the US and UK ensures.
It's very easy to rule people by pitting them against one another, and putting them in a state of fear, envy or suspicion of their fellow cit.
Perhaps things are authoritarian when a wide range of people expect abuse from the people in power, whether or not they recognize it as such.
Or, maybe it's more sinister than that, and we only truly recognize authoritarianism in retrospect.
Bingo, you get it. Put a frog in a pan of cold water, bring it to the boil. It'll stay there, perfectly content, until it cooks.