The one thing I really don't like about Calibre is how it will copy all of my ebooks into its own file organization. There is probably a way to disable this, but that is the default. Kind of irritating when you have Calibre in a cloud-storage folder and your books are also in the cloud storage, and it uses up your space with duplicates.
"There is probably a way to disable this" No, there is not, and never will be: https://manual.calibre-ebook.com/faq.html#why-doesn-t-calibr... Calibre's library is meant to be the place where you store your books. I'm curious why you want to store a second copy outside Calibre. Is it because: 1. Calibre doesn't allow you to find books the way you want? (e.g. tagging doesn't have the all metadata you want) 2. You have…
I don't even like it if a program scans my existing files to form a database without affecting them; but as long as it's not too in-my-face I guess I don't mind it so much; as I can get rid of the software and its database whenever I like, and I wouldn't notice anything was different. But Calibre decidedly takes the opposite approach, so, as the link says, I decided it's not for me. There are many parts of Calibre that I thought I might find useful, but it would be tiring to fight against a software that actively tries to work fundamentally differently than the way I like. (And I did try it, but using it felt almost as frustrating as using much of Apple software; it's an agony unless you use it exactly the way they want.) That's why I don't have Calibre installed on my computer even just for those useful parts; I just found other software to do things I like. Which is sad, because as an ebook user I really tried to like Calibre, and I really thought I would because I tend to love software that people criticize as "ugly/not modern" and "too cluttered/bloated". If only those things came with a package that didn't make it its "mission" to get me "to stop storing metadata in filenames and stop using the filesystem to find things".