Yeah, the idea that you're limited by bus width is kind of silly. If you're using ordinary DDR5 then consider that desktops can handle 192GB of memory with a 128-bit memory bus, implying that you get 576GB with a 384-bit bus and 768GB at 512-bit. That's before you even consider using registered memory, which is "more expensive" but not that much more expensive.

And if you want to have some real fun, cause "registered GDDR" to be a thing.