Fallacious argument. Just because something hasn't been successful before or people don't see how to make it work doesn't justify an existing unethical/immoral system. Plenty of people thought it was crazy to imagine a world where slavery wasn't a thing. That didn't justify continuing that system though.
There are many of examples of anarchist or pseudo-anarchist communities that exist. Many Shaolin monastic communities are anarchistic, and egalitarian depending on the sect. Some Mennonite and old world Amish communities are anarchistic also, having only collective property and some personal property, no privatization.

Some first nations tribes were pseudo-anarchist, operating as a collective with egalitarian leadership based largely on life experience and wisdom, they maintained completely voluntary relationships with other tribes in the region and had no private property.

[–] yogthos@lemmy.ml 0 points 1 year ago

It's not a fallacious argument at all. When people keep trying to do something for over a century and have nothing to show for it, then the onus is on them to demonstrate that it can work. If you tell me that walking sucks because you can flap your arms and fly much faster, then you have to demonstrate that it's actually possible to do.

Communists have built successful communist states that liberated millions of people from capitalist oppression, provided them with education, food, housing, and jobs. These are real tangible improvements that are possible following the communist model.

Anarchists have never achieved any sort of liberation at scale, and these pseudo-anarchist communities don't translate into systemic change in society.