They'll start with the same silicon design but manufacturing variability requires them to bin the chips based on functionality & performance, which is how you get all these different models.

Nobody would complain if Intel sold of 8core dies with 6 working cores as 6core CPUs. Disabling the ECC or AES-NI support just to create artificial market segmentation is an asshole move.

That is true, especially if you're in a position like AMD is where they can sell every single good chip they get into a high margin server part (which is why ryzen can be scarce). But that's pretty rare overall. As a process node matures, the amount of perfect dies will go up dramatically, but there will certainly be no price drop to compensate.

It's also true in many IBM mainframe computers for decades. Usually a lot of hardware is installed but disabled by software, an upgrade by a field technician is just the process of entering a license key. Same for many electronic test instruments, sometimes it's possible to "upgrade" the cheapest 100 MHz oscilloscope in a product line to the most expensive 500 MHz model [0] by an undocumented backdoor, EEPROM hacking, or a keygen. Extra features can also be unlocked. Interestingly, since the manufacturers' revenues come from selling to enterprise users under service contracts, they usually don't care about a hardware hackers or two on the web at all.

[0] Of course it's a possibility that the analog front-end and ADC is still binned for performance or populated with different components, so you need a bit luck here if you want matched performance.

Reminds of the Casio calculator. I don't remember the specifics, but a cheaper model is actually exactly the same as the more expensive one. They cut off a connection of the circuit board to disable the advanced functions. All you have to do is to connect the cut wires with a pencil stroke, and the calculator is "upgraded".