Earlier quoted context omitted.
I think it's fair to call all attempts so far "not reall communism". But you don't have to conclude "real communism would work". You can also conclude "real communism seems unimplementable". It is, after all, a social order that was created purely on paper and from theoretical arguments, which is ridiculous. That activity gives you something to try, but certainly not a fixed solution that you just need to implement a…
The original intention was the communist revolution would take over the whole world at once. it was never intended/feasible to be a sole communist nation surrounded by a sea of capitalist nations, but they couldn't admit that failure and pressed on anyway.
This in and of itself speaks volumes. If it were truly a viable system it could start in one country which would quickly outstrip all others in technology, culture, industrial production, quality of life for its citizens... Then all other countries would gladly follow.
But they knew from the very beginning that people who could vote with their feet, would flee that system. Countries that restrict people from leaving know perfectly well that they are doing something evil.