The fact that we need such boilerplate solution to start building a simple Mac app without having XCode in the way in 2020 means a lot about the current state of native app development.
Eeehhh, this kind of comment erases a lot of the default things you get with Cocoa/AppKit (document handling, system integration, etc). These concepts aren't as widely understood as the concepts in web-dev-land because they're implementation specific, but they're pretty well designed and genuinely very powerful once you use them.
Xcode just hides them away from you, is all.