From what I gather, the point is exactly that: That one should be aware that there are more differences than eBooks being electronic versions of books.

I think the controversial points come from people having different use-cases. I wouldn't want to not have control over my books about Hebrew numerology that took me a while to track down. I wouldn't worry nearly as much about a book about a programming language. For some books, real possession is part of the value. For others, everywhere-accessibility is worth more.

Edit: Fixed "about" -> "over";