Not that a date in a file really is valid evidence, but the point is to define when the copyright occurs. If i come back and say “well i did that same thing before you did” them it would make your copyright invalid.
If you update then you add an additional date.
I just self host gitolite. I wrote a script for archiving tagged versions to zip files as well as an optional parameter to pipe code into a markdown file and convert that to HTML for code i wish to show people. Everything else I do through the cli and have no use for a fancy UI.