> it's stupidly power hungry with little upside
Unless you specifically bought that model because you want low-latency output to an external display with G-SYNC.
I've used Asus motherboards in my gaming PCs for years, and their BIOS/UEFI firmwares there are equally awful, their Ryzen AGESA stuff has been a complete mess.
My G14 functioned just fine with G-Sync in Optimus mode via nVidia connected USB-C port (and didn't need reboot to switch between GPUs) so I never found real use for the MUX mode. It's telling that most other gaming laptops don't spend on that piece of hardware.
The switch solves a fundamental trade-off: an external port can only be physically connected to one GPU. If the dGPU you get GSYNC/etc but high power consumption if you connect an external display.
If the iGPU, then the dGPU is basically sending its frame buffer through the iGPU and is limited by it.