Well, that's what I was thinking of. Having the file itself completely backed up along with everything else, able to be downloaded to each Kobo device without actually needing access to your computer. Kind of like how you can set it up so you can download files from Calibre over wifi, only doing it directly from Kobo's servers. Hence the laboriously long post before.
I'm pretty sure you're right on the ePub not getting modified, too. Hard-coding metadata and extra information like that is
so five years ago.