Well, it's a bit of an irrelevance whether or not they state 'as permitted by law', since everything in any license is restricted by the law. Nothing changes.

My point is that Apple (and every other company) makes no attempt to define what their software is meant to be able to do. The license tries to wash their hands of everything that they can.

If I buy a camera and it can't take photos, it's not fit for purpose and I can return it. If I buy a computer to be able to (say) Facetime chat with my relatives, and it doesn't do that due to a bug or incompatibility, it's a murky legal quagmire whether or not I could get a refund.

The distinction arises when the full text of a clause is not possible to claim by law, but some weakened or lesser version is OK: If you missed the 'maximum extent permissible' part, your clause would be completely invalidated. Its a hedge.