Calibre just provides a little management on top. I use it for doing things like cleaning up metadata (making sure all books in a series have the same series name, for example), and transferring books over wifi (calibre can spin up a mini web server that I can access on the kobo).

I could get by without it, but it's nice sometimes.

Because calibre also allows me to convert other formats into epub.

Some files are unreadable garbage because of bad OCR or bad formatting or whatever. I use calibre to preview files in its built-in viewer, to see how they would be rendered on my actual reader. Helps a ton.

Some files have messed up metadata. Calibre helps with fixing that. I have encountered files that would appear as documents on my Kindle rather than books, for example. Easy fix with calibre.

Even if it is not messed up per se, I still sometimes use calibre to sometimes edit metadata to tidy them up. So that the author information between different books of the same series is the same, for example. "Banks, Iain M." for all the Culture books, rather than a wild mess of various different variations of the same name. I have also added missing pieces of information to help group books in my library etc.

It's a super useful tool. I just wish it didn't spam so many system notifications though.

I think that's probably what they're using Calibre for. That's what I do

It lets me feel the same guilt I had with a pirated music library back in the day.

Really should organize this better.

Fields are missing.

Damn there are a lot of duplicates.

Maybe I should delete all this and start over.

Calibre can do a lot of this processing better than 2008 iTunes or whatever, but I never end up enjoying the stash. It's too easy to get giant packs and have a crazy mess, not even knowing what it is I meant to read next.

The files are like 1 MB. I'll find them online again if I need them.

Mostly for file conversion