The macOS installer app uses rtf/rtfd as its EULA/readme format as well.
In fact rtf usage is all over the place on Apple platforms. Cocoa/AppKit apps can take an rtf file to present in the app’s standard About window for credits/acknowledgments and if you want to present rich text with low hassle and resource consumption, by far the easiest way is to embed an NSTextView/UITextView with editing disabled which can then have a bundled rtf loaded into it trivially (just a couple lines of code).
A WebKit webview and HTML could be used instead in these instances, but that’s significantly more heavy and doesn’t have an OS-included WYSIWYG editor which makes it less friendly to e.g. non-technical team members whose job it might be to prepare the content being displayed.
In fact rtf usage is all over the place on Apple platforms. Cocoa/AppKit apps can take an rtf file to present in the app’s standard About window for credits/acknowledgments and if you want to present rich text with low hassle and resource consumption, by far the easiest way is to embed an NSTextView/UITextView with editing disabled which can then have a bundled rtf loaded into it trivially (just a couple lines of code).
A WebKit webview and HTML could be used instead in these instances, but that’s significantly more heavy and doesn’t have an OS-included WYSIWYG editor which makes it less friendly to e.g. non-technical team members whose job it might be to prepare the content being displayed.