It's not a normal epic exclusive, like Hades, for example. Epic didn't just paid them to keep the game out of Steam (for a time), they financed the while game. Developers of "normal" exclusives get money to release their game, already under development, on EGS first. Alan Wake 2 is different, it wouldn't exists without Epic games.
Look, I like my steam library as the next guy, and would be happy to have all my games there, but in this case there is literally nothing wrong with the game being only available on EGS. Would I prefer to have it on Steam? Yeah, of course. But I also very much happy to just be able to play it, and if I have to do it on Epic, well, that's really not a big deal.
I've tried the remastered version on PS5, and it's rough. The atmosphere is great, the combat not so much. Personally, I've just watched a plot summary on YouTube, there are many, but I prefer Lady of Lore's.
Also, the game itself features a semi-conprehensive summary of the first game as well.