Going off package will at the very least increase power dissipation. Exiting a package, going across a PCB, and entering additional packages will increase capa

Going off package will at the very least increase power dissipation. Exiting a package, going across a PCB, and entering additional packages will increase capacitance significantly as well as increase resistance and inductance. This will impact performance. If the increased capacitance does not change actual operating speed, then the buffers are supplying more current to overcome the capacitance, not to mention the potential ringing and other undesired effects from the additional parasitics. There is a penalty for going off the SOC. It is not just a narrative, it is physics. The same memory address space choice is of course important, but its performance and power envelope is impacted by the SOC vs. separate package choice. The combination of M1 performance and low power has happened due to a series of choices made by Apple. Forgoing user configurability and fixing memory choices at manufacture while using SOC tech made mainstream by the phone industry is one of those impactful choices. There are of course several other important choices, but it is incorrect to discard this choice as non-impactful.