I've never understood the "PC storefront wars"....I'm not a PC gamer, but it seems unbelievably stupid.
What am I missing and why would you care?
Some people have gamed exclusively through Steam for the past 15 years and have developed a morbid attachment to it. As a consequence, since the Epic Store explicitly stated they want to compete with Steam for PC market share, they are at open war with it.
Some of these people will also tell you that that's the Epic Store launcher is a malware, that it steals your data and sells it to China, that it burns through your CPU, that it is actively eroding PC gaming culture and other hyperbolic nonsense. The truth is that the anti-Epic campaign started the exact moment Epic said they wanted to compete with Steam and began applying active competition against Valve, with the free games policy, the PC timed exclusives and offering better cuts of the profit to indie devs. That was a war declaration and from that moment on anything Epic did or said, be it good, bad, neutral or even fake, for those people automatically became evil incarnate.
It's exactly like console wars, but it's even more stupid because the thing doesn't even cost you money to begin with, you can have both for free and use one, the other or both at your leisure with zero restrictions, so why even have to get stuck on one and attempt to put down the other so aggressively.
My personal opinion on the Epic Store? It's a bit shit in terms of interface/profile management, the absense of user discussions and reviews makes it harder to investigate in advance what you are buying, and the lack of a cart is immensely stupid. Apart from that, it isn't any more or less serviceable than other launchers like GOG Galaxy, Ubisoft or Battlenet. I played a good dozen games they gave away and I was interested in anyway. Bought a couple DLCs for a game they had given for free. Never encountered any real issues.