In the past, I have considered linking to our studio's itch.io storefront from Steam. The platform fees are less on itch.io, which is a plus for us, and we distribute Steam keys with itch.io purchases, so it's a better deal for the player too. The only issue is that we have almost zero traffic on itch.io, especially compared to Steam, so linking to it from Steam could have helped, in theory. It's a pity, but I understand why Valve would do this.
If your itch store page purchases come with Steam keys then there is no problem though, is there? That's a "Steam version."