@sudoingX Achieving high memory bandwidth without the obvious area penalty can be only done with advanced packaging, which sacrifices modularity offered by DIMM/CAMM.
There are possible solutions with optics and CXL mem but we still have to wait for a while for mass adoption.
@sudoingX It requires a lot of memory PHY shoreline on die + a lot of wires on both the package and PCB + the engineering efforts to validate such complex things. Plus, a lot of the modules (DIMM/CAMM/etc.) don't offer much bandwidth compared to HBM/GDDR which require a lot of wires.