The difference here I think is that Epic Games have every intention of paying $$$ for exclusivity of any AAA game, whereas EA with Origin clearly wern't. That will put some people off, but a lot of more casual gamers that don't sit on reddit and game forums complaining probably don't care that much and will buy it from whatever store is selling it. If Epic do that with enough big games, people will eventually cave. If there are 4 or 5 big games every year released exclusively on Epic Store and in 6 months time they have feature parity with Steam, then I think a lot of people will give in. One of the unwritten rules about the world is that most people are inherently lazy and have low attention spans. They will care *a lot* about things until it directly inconveniences them, and then they give in. PC gamers will soon cave when so many of their favorite titles are exclusive to Epic store. Some will hold out and refuse to buy, but enough will cave.
What they did with Metro was pretty scummy, but I blame the publisher of that game for that more than Epic Games. Epic Games are playing their strongest card, and I don't blame them for that. The key feature of any game store is what games you can buy on it. That comes above all else. The reality is they have enough money to buy exclusivity for 100's of games. I like it because I have good faith the Epic store will be good in 6 months time, and it will push Valve to be less lazy.
To be extreme, lets pretend by 2021 that Epic has the following exclusive to their store: RDR2 PC, Cyberpunk 2077, TES VI, Division 3, FarCry 6 etc. Are people really going to avoid those games just out of some virtuous protest against Epic ? maybe 10% will. Everyone else will just cave and buy them on Epic store.