It’s disingenious to say that USSR achieved communism in 5 years between it’s inception and Stalin taking over. Especially since no one at the time have claimed achieving even socialism. Stalin took over country that attempted to build socialist society and struggled economically, and then led it in very different direction.
Early USSR was ruled by communists, sure, but that’s far from it being communist country, and even further from the country achieving communism.
I specifically spoke of the USSR before what could be construed as Stalinism, whatever that would mean. I’m also on a fence whenever direct state ownership of the capital could be fairly described as socialism, as it was the case under Stalin from what I understand, but I won’t pretend I know all too much about that part. From what I’ve gathered, that would stand against the idea that the capital is democratically controlled by the workers working it, as it would instead by controlled by the outside force not completly dissimilar to the capitalist investors (in this case, the state, directed individually by some administrators). That always stood out for me when it comes to describing USSR as socialist country.