A truly fascinating part is that feature and quality-wise EGS is still, after years of development, miles behind Steam.
Epic likely has talented devs and clearly invests a lot of money into all of this, but it took them years to finally implement a cart. It's not the end of the world to not have one, but not if you are a digital store!
It doesn't even have (or at least didn't the last time I checked) a review system. Steam isn't just a store anymore- it's closer to a social network with communities, discussions, mod workshop (which makes it stupid easy to install mods if a game supports this). With forums dying and reddit turning into whatever it is turning into, Steam forums is IT for a lot of gamers. If I see a game on sale the first thing I turn to is a review section- more often than not it's enough to gauge whether I'll buy this thing or not. And it's a nice place to ask whenever something in the game bugs our or doesn't work, or to just vent.
EGS is (or least was) really damn slow to start (never mind to launch an actual game). Linux support is non-existent.
Sure, it is extremely difficult to tackle a leader when a headstart is this large, and when people already have massive libraries of their own on Steam, but it's been what- 7 years of development? Epic had a clean slate, no compatibility to worry about and all the features their main competitor had, mapped out to copy- and they didn't even try to reach feature-parity.
Giving out free games only takes you so far when people lack the necessities to stay at your platform