- Blizzard games are exclusive to their store since forever
- EA's Origin has exclusives since they exist (or at least since 2011, not sure if that's from the beginning)
- Valve's games are Steam exclusives
Epic has time-exclusives, offering a very good deal to game makers, and is a quite good way to compete with Steam. If you're not happy with their store, just wait a year and you may buy the games you want on other platforms if the developers decide to do so.
Those are all examples of companies creating their own store so they can sell their products directly wihout paying someone else. This would be equivalent to Epic requiring to you to use their store to play Fortnite. I think that is shitty behavior but as you said, has become standard.
What Epic is doing, and the main reason they are being critisized, is approaching smaller developers and bribing them to not sell on other stores even if, in many cases, they had already promised their customers to sell on their stores. That is a wholly different level of scumbaggery.
There is no bribing here. They offer a better deal to developers than the competition is willing to do. And they have exclusives limited in time, the games aren’t blocked forever on their platform. That’s a good thing for developers, making and selling games is a bad business for a lot of people, Epic is offering very good terms, in exchange for a 6 months to 1 year exclusivity.
I personally see it as very good on the long term, that’s how you compete with a monopoly like Steam. That means more cash invested in making games, more options for developers, more options for users.