I'm not sure I'd agree that the Mac toolbox is primitive. Reflowing forms to reflect a resizable window wasn't a common technique at the time; Macs had a predictable screen size and DPI. Abstracting the layout of a form from code via a resource was a very forward-thinking approach for the day. Among other advantages, fiddling with ResEdit was very empowering for users who might not even have access to the source code of an application!