As a user of both EGS and Steam, the one thing that EGS doesn't have that Steam does is multi-threaded downloading. Steam can saturate any connection I've thrown at it, whereas EGS gets a few-hundred mbit/s and saturates a single CPU while doing it.
Perhaps game devs get a whole bunch of "gee whiz" features from the Steam Platform that Epic Games doesn't provide, but I -personally- couldn't care less about those.
You don't need multiple threads to saturate a gigabit connection. Even many embedded SoCs can do it.
That said, Steam has a rather absurd CDN.