It's worth keeping in mind that the chipset has zero involvement in ECC. The CPU is directly attached to the memory slots. They're using the chipset as an expensive dongle.
Well, the chipset does enable error detection and correction features, because it is the responsibility of the chipset to raise certain interrupts or assert this or that signal in certain error cases. You may view this as artificial segmentation but without the more advanced management engine in the Q680 and W680 chipsets, the Z690 and all lower chipsets that contain the simpler "client" i.e. consumer management engine can't enable ECC.
You're saying the memory controller sends an error signal to the chipset, and the chipset sends it back to the CPU package?
Even so that's an extremely trivial task. It doesn't need a "more advanced" anything. It needs them to not deliberately disable the code or remove the tiny tiny amount of circuit.
They do it with rear I/O too. Motherboards with anything but workstation or flagship consumer chipsets typically have an anemic port selection, which is silly because for many half the reason to choose building a desktop over buying a laptop is to be able to plug in a lot of stuff without a bunch of hubs/docks/etc.
