Maybe that would force manufacturers to be in a position where they can truthfully say "we can't do that". I'd prefer that to the current situation where Apple basically has a backdoor they're just trying to keep for themselves.
For all we know so far, Apple could still provide a signed firmware bypassing the bruteforcing delay implemented by the Secure Enclave.
Probably not easy and not on mass scale. It may even need to have to see inside the silicone itself. Which is expensive and hard. But as long as the keys are on the device or in possession of apple - they can be extracted.