Architecture astronauts take over

I read his articles, and am still uncertain of the benefits. CUPS talks fine to remote printers. He admits CUPS integrates with polkit. Right now I tell my app to print, answer the various questions (# of copies, printer, etc), and off it goes. I go back to my app,and sometime later the printer prints my work (asynchronous from my viewpoint).

So other than adding another layer between the application and CUPS, what does printerd do?