> shoe horn multiplatform UI into MFC

This is nonsensical. What are you even trying to say here? MFC isn't available on macOS or GTK.

> Just look at Unicode. It’s an unholy mess.

This seems utterly unrelated to the issue under discussion.

> Qt does what it does, even if the approach is not the same (arguably superior), there’s also Tk. There’s also libui and IUP.

None of those allow a single codebase to compile on Windows, Mac, and Linux, and get native UI elements on each.