Earlier quoted context omitted.
Well, no… Anarchism can be achieved via parallel construction, provided that the existing society doesn't fight back. For example, mutual aid networks (as described by Peter Kropotkin). And an anarchist society could transition to a communist society (or pretty much any other society) – but even Friedrich Engels' "withering away of the state" route to communism (attributed to Karl Marx, but Wikipedia disputes that it…
Sure and if I claim that you should do a 1-handed handstand and say 'communism' three times in a row, it will surely create communism right? I can even write it down on a piece of paper and call it a 'manifesto'. But in the actual real world writing stuff down doesn't make it true at all, even if the person that wrote it is famous. > For example, mutual aid networks That in reality have never even come close to achie…
I say "even" because afaik Marxists don't seek to destroy the state: they believe the destruction of the state is inevitable (dialectics!), and seek instead to win battles in the class war – my "even" applied to the "withering away of the state" idea, not to Friedrich Engels himself. (I'm not familiar with all of his ideas.) Marxism–Leninism is the "the Bolsheviks were right all along" belief system, but is quite different to classic Marxism.
In the real world I don't think we'll ever have a group, region, or territory governed by any pure ideology, so I agree that a state of anarchy, or a classic communist society, would never happen in real life. That doesn't mean it's worthless to think about the ideas, any more than it's worthless to talk about uniform point masses on a frictionless inclined plane.