What is the financial benefit to Intel in artificially limiting its CPU sockets like this? Logic and reason would have me believe they'd want to sell as many CPUs as possible, and keeping the socket compatible for as long as possible would seem logical. My thoughts on reasons they might have done this. I honestly have no idea, these are just uninformed guesses. - The Charitable Answer: There actually is some sort of…
Intel actually intended for LGA1151 to remain unchanged for Coffee Lake but found out late in the testing process that many existing motherboards did not have enough power delivery capability to support the planned 6 and 8 core parts. Hence the decision to lock them out in software only. They are probably aware of the bad optics but decided that it’s better than trying to deal with the RMAs later. It’s very similar t…
Of course, the P67 chipset was trivially electrically compatible with LGA1156 CPUs; Asrock's P67 Transformer motherboard proved that conclusively.
That said, the main problem with 1155 was their locking down the clock dividers, so the BCLK overclocking you could do with 1156 platforms was completely removed (even though every chip in the Sandy Bridge lineup could do 4.4GHz without any problem). This was the beginning of the "we're intentionally limiting our processor performance due to zero competition" days.
> LGA1150: Introduction of on-die voltage regulation (FIVR)
Which they would proceed to remove from the die in later generations, if I recall correctly. (And yes, Haswell was a generation with ~0% IPC uplift so no big loss there, but still.)