USSR itself did acknowledge that whatever they have is not communism. Because they knew the definition, they knew that it's a utopian society which, as you mentioned, doesn't use money
The rest of the world had to name this regime somehow. Since there was only one party, the communist party, the west named the regime "communism".
Now we have a word with different meanings, depending to whom you speak. Certainly makes discussions between ex-ussr people and americans hard. I remember how my school teacher got irritated when we asked her "how was the life under communism". "We never lived under it, we lived under socialism" she said
To sum up, this is not a "no true Scotsman" situation, since the observing part of the world decided to extend the meaning