Most people who want to are capable of using calibre. I have shown at least 10 and they have no real problems with it.
I am also pretty sure that not one of the 10 would have stumbled on it on their own or gone to the bother without help or prompting.
I found calibre within an hour of buying my first reader. I then proceeded to flail around in every direction but the right one for several weeks IIRC. Although I was a programmer for quite a few years and bought my first computer in the 70's I was doing things like appending the series names in the book titles, saving to disk and then deleting one bunch of books and starting on the next. I cringe in embarrassment when I think back on it. I talk to a lot of strangers with ereaders where I work, maybe 5- 10 a week, and not one has ever heard of calibre.
Then again I doubt very much whether the kindle owners I encounter, have ever heard of Baen or the other stores selling mobi books. Many are aware of PD sources like Gutenberg but not that happy with them.
I have asked people where they get their books. My overall impression is that kindle owners buy from Amazon, Kobo owners buy from Kobo, and Sony owners get the majority of their books from the library. Tablet owners buy from Kobo or Amazon. Never met a person who bought from Sony. Of course trying to be subtle I say, if you don't mind me asking, where did you get it (the book). I've only actually seen one Nook so no idea what they do, but my guess would be B&N.
I do ask because I am curious and it is an easy way to interact with a customer which generally results in a bigger tip
. And I often suggest MR and calibre to them.
The people I see are approximately 60% US citizens, 30% Canadian, and 10% European with maybe 1% Asian, Australian combined. Most who I see with ereaders are retired people making the big trek north.
The books they are reading, if they are not lying to me, are Dan Brown's, Inferno, various James Patterson, Game of Thrones, Sookie Stackhouse, and a couple of little old dolls admitted in hushed tones to be reading 50 Shades of Grey, but not sure they liked it. Closest I came to classics or older works was one Shogun and a Louis L'amour. They are al reading the same thing.
I don't think that Amazon is doing anything wrong or controlling by only selling kindle formats, any more than Kobo is doing wrong by only selling epub/kepub. Butchers farmer's do not necessarily sell fish although they can if they want to.
At this stage in the game it might result in claims of trying to corner the market if Amazon started selling epub, and if the other major ebook retailers started selling epub, then possibly Amazon would start selling mobi al least. No law against it, but the last thing the other retailers want I am sure.
My opinion (and it is only an opinion) is that Amazon and Kobo are sitting comfortably and Sony is maintaining a market position in case they decide to actively pursue the ebook/reader market and more power to them if they do.
But my overall impression is that people buy ereaders for convenience and if they don't find it easier than going to the corner drugstore to buy a book they won't bother.
Removing DRM or hunting down small book retailers in the vague hope that they will have the latest bestsellers is not on their list of preferred things to do.
Helen