Why wouldn't Steam like the business model:
A) Develop the game, early release on a different site.
B) Release the final version on Steam.
From what I can see so far, people on Steam want the final version. Yes, steam can deny keys - but they haven't so far. Out of interest sake, are you in the SteamWorkshop / released a game on Steam?
Viewing post in Indie games, itch & Steam
its the same story i keep hearing, they make a early release here on itch.io and then they go to steam for final. You forgetting that most of itch.io customers hate steam and steam customers hate other platforms. You are clashing two things that makes everyone angry. You need to understand your customers as well as balance it because right now most of the customers won't go to steam while steam customers will not find you due to being so new.
Hate is such a strong word. We're talking about computer games.
Yes, I need to understand my customers but they also probably should understand the processes involved. And I think the numbers of people who hate - are fairly low to the number of people who love games. And as other have said - it comes down to the advertising which helps with being seen.