I imagine there is some trade off to be made between increasingly surgical disabling of components and avoiding a menagerie of franken-SKUs. Presumably the fault rate is low enough that tolerating a single GPU core drop takes care of enough imperfect parts.

Perhaps there is fault tolerance hidden elsewhere, e.g. the neural engine might have 17 physical cores and one is always disabled. Although this seems unlikely as it would probably waste more silicon than it would save.