> The 4080 is a 4090 die with some SMs disabled.

The desktop 4090 uses the AD102 die, the laptop 4090 and desktop 4080 use the AD103 die, and the laptop 4080 uses the AD104 die. I'm not at all denying that binning is a thing, but you and other commenters are exaggerating the extent of it and underestimating how many separate dies are designed to span a wide product line like GPUs or Apple's computers/tablets/phones.