@Odysseus Oh boy... this... so...
Unlike... the world of console games... hardware exclusivity isn't really a *thing* in PC games for obvious reasons. There can be *some* form of exclusivity in a way when it comes to where games are sold on the internet. Like... in terms of game publishers having their own digital store-fronts.
The *vast* majority of game companies don't do that. Or rather, they don't *just* do that. The big ones (like Microsoft and Ubisoft) will have their own storefronts for the games they publish... but then they'll also put all their games up on Steam and GoG which are... essentially the two huge game marketplaces for most of the internet. Those companies *do* take a percentage cut for hosting games on them. However, they're pretty much *fine* with publishers putting their games up for sale on marketplaces *other* than on Steam and GoG and a lot of times... when you buy games directly from a lot of publishers without a digital store front.. you'll get the option to buy a Steam and/or GoG key. Anyway. Point being, yes, Steam and GoG take a percentage of game sales... but they also don't care where else publishers sell games. Also, Steam and GoG do a lot more than *just* sell games... they also host modding for games and supports Linxi and forums and reviews, etc. Oh, and they have a shopping cart...
Epic Game Store is... a lot more controlling over how (and when) publishers can publish games *outside* of Epic. On the one hand... it does take a smaller cut of game sales than Steam and GoG do. Supposedly so it's better for game publishers. Problem is... *how* Epic goes around getting "exclusives" for itself has been pretty sleazy at times. We're talking... kickstarted games that said they were releasing on Steam deciding after the kickstarter was closed that they were only releasing on Epic. And... other kinda weird stuff. There's also a lot of incentive for companies using Unreal (also created by Epic) to use only the Epic Games Store.
And that's not getting into how the Epic Game Store doesn't have some basic things you'd think to be on a gaming marketplace... like a shopping cart, or any place to leave game reviews... or a place for game players to leave comments about the game. This leads to the weird situation where people are going to Steam to make forum threads for games that aren't out on Steam yet because they're out on Epic and there's no way to communicate over Epic. The storefront is just... so bare of what are now *essential* tools for an online marketplace it's really baffling. And there's no roadmap for when any of these issues will be addressed.
When gamers *do* bring up these issues... they get blasted by Epic's CEO about making mountains out of molehills and a lot of other really telling comments that suggests Epic really doesn't care about the people *buying* games on their storefront. They just want to make money off selling games there... and that means getting people to the storefront even if it's a really bad storefront. So they've openly acknowledged they're competing based on the *content* that is sold there and nowhere else.
You've effectively got a company that is trying to make a service a lot of people don't want to use because other companies have been doing the same service for *years* and are a lot more competent at it. So the not-so-great service is trying to get a monopoly on the *content* it's selling on it's service. This makes the people who wanted to get that content more than a little pissed off because it feels like someone wants to make a monopoly in an industry that (at worst) has an accidental monopoly (trying to get more accounts on a game marketplace than Steam/GoG have... good luck) but it's really is more like a free market with Steam/GoG as the general marketplaces *everyone* uses. Sellers and customers alike.
TLDR: Epic Game Store is trying to introduce to PC gaming the kind of exclusivity that Sony and Nintendo enjoy on consoles. They are doing this by finding games people *want* to play and then making sure they aren't sold anywhere else but Epic... Only Epic Game Store is a shitty platform to buy *anything* on and PC gamers... kinda like the idea of buying their games from the marketplaces where they want to buy them like they've been doing for the last 10+ years. Cue stuff like boycotts of games on the Epic Game Store until they lose their timed exclusivity and can come to Steam/GoG where people have been building their game libraries for the last 10+ years.