Revenue sharing is an essential feature that's missing from itch.io, and it's starting to make me pretty frustrated that it hasn't been implemented yet. As a musician, I can't really offer my services to anyone for a fair fee if we're only doing a single upfront payment. It would cost too much for most indie devs to pay me something reflecting the amount of labor I'm putting into the music. If itch added revenue sharing, I'd be able to collaborate on a lot of projects with minimal upfront fees, because I know I would be included in future sales.
I think most people here aren't "business" types; nobody here wants to be an accountant who has to manually pay their collaborators, which is stressful and nerve-wracking. There's already revenue sharing for bundles, which I've benefited from immensely many times; I fail to understand why it can't be implemented for individual projects, if everyone involved has an itch.io account they've uploaded their tax forms to and stuff.
I would really like to see itch.io break the silence on this topic. I feel like a lot of people are asking for this, and its absence is preventing itch.io from becoming a more legitimate and compelling option for a lot of devs who can't pay their collaborators upfront, who don't want to manually pay people themselves.