People should never buy an ebook which they cannot make a copy that is readable anywhere, extra steps required or not. There are so many disadvantages to even list.
an ebook that's yours to download is one thing, an ebook that you lose access to once your subscription ends is another. vendors love locking you into a platform and having you "buy" content that's never really yours.
Mu? With a book I’m not bound to a technologically complex device I can’t repair, let alone to somebody’s willingness to maintain a remotely accessible database somewhere on another continent. At worst, I can mount a camera above my desk on a microphone arm and fire up ScanTailor. Even if it’s amazingly tedious work.
When I can get a godsdamned file and view it on whatever I want with whatever program I want, sure. But I usually can’t.