Why? It seems like to me that the "Apple should buy Intel" argument would apply equally to any Apple vendor from power supplies to glass providers. Apple already gets most favored customer pricing. Apple success is to take those materials and add value to them. Apple does that quite nicely.
The only benefit that I can see Apple could gain would be they could have their way with Intel fabs and build anything they want in them. However, if Apple were the owner of those fabs and did that, they would also not make the $$$ that Intel makes on those fabs building other devices.