I understand your reasoning but I really hope you'll reconsider this decision. I don't use Steam for NSFW games for various reasons, so it being the only way to access the complete game version means I simply can't access it. I paid for this game on Itch and I will gladly pay another $5 for a final version, but I won't buy it on Steam.
You have other alternate options here. Make a separate Itch page just for the paid version (like how One Potion Please does it) or maybe make a Patreon with the game on there accessible to a $5 tier. Hell, even make a Ko-Fi and just email a MEGA link to everyone who donates $5.
I'm sure these are all various flavors of pain-in-the-ass, but I'm looking at the comments and seeing a lot of people who want to support you and can't do it through Steam. I hope you can find a solution.