Especially if you have an implement on there (for weight or just because). It gets that out of the way in the high park position. Even on high you'll occasionally "run aground" of things.
Even if there is nothing on it, keeping the arms high keeps them from getting bent.
I generally always have something back there for ballast, usually a rear scrapper blade, so I just keep the attachment where it needs to be so it's out of the way.