We may be nearly on the same wavelength in some respects, but consider this common scenario: I have a new US FDA Class II product idea, which I proceed to design. It hasn't yet been approved for marketing and I'm not marketing it yet, but after I complete the design I'm going to prepare a 510(k). Do I need to follow design controls in the pre-marketing design phase in order to have the requisite documentation for that 510(k) to be accepted, and to pass an early inspection in relation to that 510(k) if in some eventuality such an inspection should be conducted, as sometimes is the case internationally?
I think the answer is yes. If it were no, the great majority of Class II products would be subject to design controls only after they are designed. That, I'm pretty sure, is not US FDA's interpretation of the relevant provisions.
Maybe US FDA doesn't require/expect design controls for products that are designed more than X time before marketing begins, with X being a relatively long time. I've never seen any indication of such a policy in my pre-marketing-approval interactions with US FDA, though.