Outer Wilds barely hit its fundraising goal on Fig, the crowdfunding platform where they have to pay back some money to investors. That goal was 125,000 dollars. This game has been in development for quite a while and there are 12 people on the team. This game has already cost several hundred thousand more dollars than they made from Fig. I feel it basically goes without saying that even with the money they're getting from Fig, AnnaPurna, and Epic, the cofounders haven't seen any money from this yet. For better or worse, they have clearly been doing everything they can to just ship this game. So.. I don't blame them for going this route (and I doubt they took it unilaterally or lightly).
If this is timed exclusivity.. eh. It's still coming to Steam, just not on the release date that was definitely never a guarantee on any crowdfunding site. To be clear, this still sucks. I think Epic should fund refunds for people who want it AND provide backers an EGS version key, particularly for people who simply can't play the game now. But ultimately, I don't think the hate for the devs is deserved in this situation.