Good question. Possibly because that approach wouldn't work on readonly files. (But in the case of readonly directories .DS_Store wouldn't work either). Possib

Good question. Possibly because that approach wouldn't work on readonly files. (But in the case of readonly directories .DS_Store wouldn't work either). Possibly because not all copy programs copy metadata. Possibly it's just technical debt: .DS_Store was added to MacOS before xattr and rewriting the Finder to use xattr is not high priority.