I maintain the dies, themselves, aren't particularly scarce. Just look at pricing of the i3-14100. Newegg has it for $143, which is $111 less than they wanted for the i5-12600:
Yes, two of the P-cores have been disabled. Can it really be true that yield on P-cores is a problem, when there are C0 dies (8P + 8E) selling for less, and yet have all 8 P-cores enabled (e.g. i7-12700K)?
My guess is that probably the corporate Windows 10 client market is the main destination of most i5-12600 CPUs, and they're probably neither terribly cost-sensitive nor price-responsive. It's not a great gaming CPU, due to relatively low boost clocks and smaller L2 cache than Raptor Lake. I wish they had refreshed it with Raptor Cove cores, but we might end up seeing something of the sort from Bartlett Lake?