I think I can say the link you provided is about Mobipocket and kindle. I didn't see anything there about epub.
This is the one big downside of readers. Once you pick a reader you are picking your poison. For the most part you are tied to Mobipocket, epub or kindle. Not necessarily a bad thing unless years later you want to change readers or you want to upgrade and the upgrade uses a different DRM format.
I accept the fact that publishers want to protect their intellectual property and revenue stream. I do believe companies have to find the way to allow us fair use of the product. By the way O'Reilly the publisher of software development books sells them without any DRM. It is totally open. I now am assured I can transfer the books to a new reader when I get one. I have great respect for O'Reilly respecting the customer. I will never give away any book but especially an O'Reilly book.