It's generally an Ultraleft position that is convenient to take for Western "Leftists." The Dengist reforms were a return to Marxism as opposed to the later end of the Maoist era, where they tried to implement Communism more by decree than degree. Establishing Communism based on fiat goes against Historical Materialism.

The reason it's convenient for Western "Leftists" is because it supports US Imperial Hegemony, so these views aren't as heavily combatted by Western media. It's idealist, not materialist. It's what happens when you remove Historical Materialism from Marxism and re-insert idealism and utopianism. A good article on the concept is Why do Marxists Fail to Bring the "Worker's Paradise?" They think, through chauvanist analysis, that any AES state that isn't the immediate pinnacle of civilization is a betrayal of Socialism, not realizing their own betrayal of the Global South in defending Imperialism side by side with neocons.