I've not had to consider that before. I would say it's probably not a good idea though. Most played games will be Web ones, and I'm not sure itch will allow you, at least not nicely, to handle multiple windows through the browser.
And UX on desktop would not be great.
If your goal is to get around the resolution limit by using the multiple windows, then people rating wouldn't look on that too well.
A way I could see something like this working though, would be like tooling, where each window is a separate thing. Such as a pop-out level editor, or maybe a code/sprite editor for a fantasy console, etc.
Just be aware of poor ratings if people don't agree with such an interpretation.