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.