There's nothing artificial or imaginary about the extra costs of using a CPU socket with a 512-bit memory bus rather than a 128-bit bus. Bigger sockets and more

There's nothing artificial or imaginary about the extra costs of using a CPU socket with a 512-bit memory bus rather than a 128-bit bus. Bigger sockets and more memory slots make motherboards significantly more expensive, and the wider memory controller and faster interconnects makes a CPU more expensive and power-hungry. Those costs affect the whole platform, including entry-level systems that don't have enough memory to populate all those channels and ones that don't run workloads which would benefit from the extra bandwidth.