I think the part people are frustrated with is the fact that the itch.io version won't be feature complete compared to the steam version. I.e. no multiplayer.
yeah because thats not possible on itch, if you just read the blog post you'd realize why
He could give his early supporters steam keys - this turns a $1.20 into nearly a $5 purchase - and honestly I would not have bought this game at $5.
I did read it, I'm just explaining why people are frustrated.