They are rarely added or removed but the list can certainly be displayed different ways: on a single line, one name per line. If the authors are tagged separately it might also be easier to do something clever with their name like generating a google search on their name, linking them to a bibliographical DB or just to their bio's.

Granted it looks like a simple split /\s*,\s*/ would give you the list but the risk is that if an author name one day happens to include a comma (Sergio "The Good, The Bad and the Ugly" Leone maybe ;--) then your code will fail silently.

In the end it is a trade-off between conveniency (not tagging individual author names might make it easier for the initial typist) and power.

For people list I have nearly always seen each name tagged though