I chose the 3090/4090 because it seems to me that this machine could be a replacement for a workstation or a homelab rig at a similar price point, but not a $100-250k server in a datacenter. It's not really surprising or interesting that the datacenter GPUs are superior.
FWIW I went the route of "bunch of GPUs in a desktop case" because I felt having the compute oomph was worth it.
I agree that compute is likely to become the bottleneck for these new Apple chips, given they only have like ~0.1% the number of flops