These AMD APUs are basically a GPU with a Zen core attached. It makes sense for them to have GPU like memory requirements. It is a niche small form factor product built around a mobile APU that doesn't currently work with socketed ram.
I remember when I had seperate sound card, network card, 2d graphics and 3d graphics. Sure it was all seperate upgradable but it was also a bit shit.
I have an AM4 motherboard here that had 3 CPUs and 3 gpus. Really awesome platform and I want more of that but as technology changes I don't know how long that will be practical. Integrated GPUs might make dedicated irrelevant in a few years. And possibly nobody needs more than 128gb of ram.