Looking at Geekbench charts, I see that my Samsung phone has a faster processor than my $3000 gaming rig, and it sure as hell draws less power ... so why aren't datacenters just use phones instead of Xeon and Epyc servers, what am I missing?
You need to be competitive on single thread performance to have a chance at datacenter. Amdahl's law is still very relevant. Up until very very recently, the CPUs were not up to par.