This is exactly what Apple has done, but it does mean soldered memory, as socketed memory at these speeds still hasn't happened. In the server market that is pretty unpopular (even the hyperscalars are apparently reusing DDR4 with CXL in newer machines). DDR6 apparently has twice the memory bandwidth of DDR5 so that will bring it back in line, to around 1TB/s for 12 channels, so comparable but still with standard memory sticks.
Mac ultras would be great if they offered pcie slots to put nvme drives on and ideally an infiniband network card.
Vera doesn't use soldered memory, it uses SOCAMM2.