Because, Winback!ruptor wrote:Why is an RTC useful on a stand alone computer? Is it so you know when to make a cup of tea?

When I had my QL attached to a Miracle Systems Hard Drive, I wrote WinBack to check if the last modification date was more recent than the backup date -- both stored in the file header. If so, that file was selected for a backup, otherwise, it wasn't.
Also, when using make to build software, it needs to know which files are more recent than the executable and/or the object files that make up the executable. Having the date corectly set is most helpful in those cases.
There are also some "activity planners" software around, so they definitely need the date setting.
HTH
Cheers,
Norm.