@RustyCrab The obvious devil's advocate is that hardware has a monetary cost that software does not and our current economic system is based on making the cost of production as low as humanly possible (or lower) that the increased cost and complexity of having everything apart isn't worth it.
Plus if I remember my computing history a lot of things that used to exist on the motherboard (the old "north bridge", memory on newer ARM MacBooks) got moved to the CPU package because the speeds required were so high it that separating it wasn't just a cost problem but also a latency problem because electrons can only go so fast. The tolerances for the most recent PCI-E generations is extremely close to being 0 because if one of the circuit leads is a micron too long the timings will fail

t. Studied this kind of engineering in university [which means nothing]