[User23]

Yes. Chip fabrication is super sensitive to the condition of the silicon wafer used. Chip companies talk about yields, because some percentage of chips can't, for example, be run at the highest clock rate. Indeed, some can't run reliably at all. If there is a microscopic flaw on the wafer that ends up being where one of the cores is located, disabling that core altogether is an option to keep that silicon marketable.