> Just like Intel not shipping ECC for client SKUs when DDR5 design makes it really necessary

The ECC in DDR5 is on-die ECC and that's not "real" ECC, it's what DDR5 needs to not fail. Side-band ECC is the standard method, employing extra memory chips and 72bit memory. OEMs mix these in the marketing materials to fool the users into thinking they buy the better option.

Yes, here I'm referring to actual ECC, not the on-die ECC. All DDR5 chips have on-die ECC as a prerequisite just to reach error levels comparable to standard non-ECC DDR4, but from a hardware analysis perspective, even with the on-die ECC, DDR5 still needs ECC more than DDR4 (which already needed it).