The Mac would be a better comparison than iOS. On the Mac, developers are free to circumvent the Mac App Store entirely and keep 100% of the revenue (minus whatever it costs them to process the payments, distribute the binaries, etc.)
And in fact this change specifically excludes Xbox (and, curiously, all games in general), which is the (remaining) Microsoft platform that's closest to iOS in terms of being locked down.
Mac is not a better comparison because we're talking about the Microsoft Windows Store in particular here, not "all software that can be run on Windows computers."
You are still free to circumvent all royalties to Microsoft by not listing your product on their store at all and marketing externally and keep 100% of the revenue, which is similar to the Mac, but the Windows Store is more akin to iTunes or Google Play.
And in fact this change specifically excludes Xbox (and, curiously, all games in general), which is the (remaining) Microsoft platform that's closest to iOS in terms of being locked down.