This appears to be the eReader-like approach now used only on the Nook for ePubs, see
Adobe and Barnes & Noble eBook Collaboration.
What is new, if the article is correct, is that Adobe is suggesting that the AdobeID and its password are strong enough protection. B&N is using your name and credit card number as the username and password. This is the same scheme, all that differs is how likely you are to distribute the password. It might be viable, given that passworded PDFs are sometimes used as ebooks.