Communism was a horror for multiple reasons, but two big ones were: the planners didn't have the data or ability to actually plan (the interactions in a market economy did that much better), and not doing the work you were assigned was a crime (that is, slavery).
AGI and AGLabor solves both these problems. If you don't need workers, you don't need to coerce them into work. And planning and massive data collection (and management in general) sounds like something AGI would work very well at. The conceit that the lower classes are disempowered before the capitalists never struck me as well founded.