So literally, VW partially donate Veyron to their clients, selling it under-priced.
I think, same happen with Apple M architecture - it is extraordinary and different from anything on market, but Apple sell it under-priced, so to limit losses, they decided to limit it to very few models.
How such things happen? Well, hardware is hard - usually so sophisticated SoC need 7..8 iterations to achieve production, and this could cost million or even more. And mostly happen problem, just low output, mean, for example you make 100 cores on one die, but only 5..6 working.
How AMD/Intel deal with such things? It's hard, mean complex.
First, they just have huge experience and very wide portfolio of different SoCs, but used some tricks, so could for example downgrade Xeon to Core-i7 with jumpers.
Second, for large patterns like RAM/Cache, could disable broken parts of die with jumpers, or even could disable cores. That's why there are so many DRAM PCB designs - they usually made as 6 RAM fields with one controller, and with jumpers could sell chips with literally 1, 2, 3,4,5 or 6 fields enabled; some AMD SoCs exists with odd number of cores because of this (for example 3-cores), and other tricks, which could made some averaged profits from wide line of SoCs.
Third, for some designs, Intel/AMD use already proven technologies, like Atom was basically just first Pentium on new semiconductor process, or for long time, I7 series was basically Xeons previous generations.
Unfortunately for Apple, they have not such luxury to make wide product line, and don't have significant place to dump low grade chips, so they limited M line to one which as I think just appear to have largest output.
From my experience, I could speculate, Apple tops consider to make wider product line, when achieve better output, but for now without much success.