Can't you also distribute it paid on itch and offer the previous versions as a "demo"?
Viewing post in Multris v1.0.7 released on Steam! comments
I could, but it just starts to become a hassle to maintain two separate store pages. Making sure images on both pages are up to date, posting update logs to both platforms, making sure the game versions are up-to-date on both sites, it becomes really inconvenient.
That being said, I do really like the itch.io platform for Early Access games. When I start development on my next game, of which I already have an idea for, I will most likely do the same thing I did with Multris: Put it up for free on itch.io for the first several versions until I've gotten enough player feedback implemented that I think it is ready to sell for a price tag on Steam, where all future updates will then be posted.