Incompetence is a matter of degree, as is famine. I'd be the last to say that Soviet economic competence was close to ideal. Indeed, it was significantly worse than even Tsarist economic management.
But food shortages aren't the same as famines, and in the famines (assuming we're talking about the famines of the early 30s), economic incompetence wasn't the primary driving factor, although this may be simply a case where we simply have different definitions of incompetence. Stalin explicitly wanted millions of Ukrainians to die as collective punishment for not being sufficiently red, and it's fair to say that he thought it was better to have a dead peasant than a peasant not part of a collective farm, where they and all their activities could be made easily legible to the Soviet State and placed under bodily control.
Those millions of deaths racked up could have been avoided if Stalin had wanted to, even within the rubric of central planning. It's really not even a matter of the famine being something that could've been "averted": the famine wasn't a natural occurrence but something engineered.
Central planning, particularly central planning under a dictatorship, being highly conducive to psychopaths killing millions of people is something I'd agree with, but it needs explicit argumentation.