It was much better for gaming than Linux, so far as natively-supported games (so, not counting Wine) until MacOS dropped 32-bit support. Now, yes, it's far worse for gaming than Linux.
FWIW, tried to play Borderland 3 this week with a friend and he couldn't get it to connect, at all. Booted into Windows, worked fine (I was on Windows).
So yeah, the store works - but that doesn't mean the "Linux games" work, or work fully, with network.
Are you saying BL3 not working on Linux is Epic's fault? Or just that they shouldn't be selling stuff that doesn't work?
If the latter, I agree but no storefront actually meets that standard right now. Valve happily sells stuff on Steam that barely works on Windows and before the new refund policies they'd perma-ban your account if you tried to refund a broken game.
I'm simply saying "the store works on linux" is too simplistic. It might be true, but people might think that means the (linux) games on it might work. It's not about blame. My friend was happy he could play it under Linux. He was less happy he had to reboot and patch Windows to use multiplayer.