And they will continue to do so, once Epic doesn't pay them more than they'd make elsewhere. Why aren't you complaining about other games which only release on a single platform?
It's the same reason, why era is overtly negative about Stadia and Apple Arcade: They don't already own the platform, so they won't go to war for it.
The last two are weird arguments (and I say that as someone who uses both Linux and a DS4). Do you complain about XBox-esxclusives the same way? Most of your arguments apply to console exclusives as well.
I don't like exclusives either. If it was up to me, all games would release on all platforms. It's not up to me, however, and that's why era has rules against console warring and port-begging, to keep these kinds of discussions from clogging up threads about games.
Publishers have no obligation to cater to your interests, their primary function is to do what's best for their developers. You are free to not buy the game, of course, and even voice your thoughts on that. But why do it in a game announcement thread and completely drown out any discussion about the actual game? YOu don't do that for PSN exclusives, why do it for EGS exclusives?
As a consumer, it makes zero difference to me why a game is exclusive to Steam. If I can only buy it on Steam, I can only buy it on Steam. The possibility of the publisher releasing it on itch doesn't mean shit to me, if they don't make use of it.
tl;dr: hate the EGS and it's money-hatting all you want (more power to you and I mean that), but this thread is about Observation and not about the EGS.