I think the idea is that single-socket EPYC CPUs beat many Intel dual-processor setups. If you break it down by sales numbers, a single EPYC might beat the most popular dual-Intel platforms. http://images.anandtech.com/doci/11551/epyc_tech_day_first_s...
The lower end dual socket E5-2xxx are the most popular servers. AMD claims they can win on performance, match or beat maximum memory, and win on perf/watt when comparing a single socket AMD to a lower end dual socket Intel.
Seems reasonable to me, I'd consider getting a quad system in 2U amd system with single sockets if it beat price and perf of a quad system in 2U intel system with dual sockets.