MacOS also used to store things like the icon and position on the desktop in the resource forks. As commenters here are making clear, they have been repeatedly

MacOS also used to store things like the icon and position on the desktop in the resource forks. As commenters here are making clear, they have been repeatedly implemented across a variety of operating environments because it really is useful being able to store additional information alongside the single stream of bits conventionally thought to make up a file. Even on Unix :-)