There are a lot more pre-supposes than just those ones, Lazyscot. And that, to me, is the whole problem with DRM. For example, eBookwise has a secure format that pre-supposes you will never buy another machine again! Each file is hard-linked to the device on which it it is purchased, and cannnot be read elsewhere. So if your machine gets lost, stolen or broken, and you buy another one--EVEN FROM THEM--you can't read your legally purchased content on it. I think it is absolutely criminal that they charge full price for such things. They should charge $1-2 and call it a rental, but a sale, to me, says I own it and can do what I like with it. I only bought one title from them before I figured out the scam, and if I ever do come across that title in a pirated form (not that I look for pirated stuff, but if I ever do come across it) I would feel fully justified in downloading it so I could still read my legally purchased book.
Or how about the computer program 'shareware' schemes of old, where the program has parts locked unless you send a cheque to Bill Smith at 3434 Jones Street in Chicago? Years later, someone might download this program (nothing dies on the internet) and Bill Smith may have moved on, so you have no way to unlock the program. Or how about the Google Movies system where it pings the server every time you watch---pre-supposing that years from now, this server will still be running so you can watch your bought and paid for merchandise?
It's absolutely ridiculous. I have only ever found two DRM schemes I can live with: the public library, where the book (which you have borrowed, not bought) is set to expire after the loan period is up, and the eReader one where there is no limit on download amounts or to how many devices, but your credit card number is imprinted into the file and is needed to unlock it the first time you read. That is fair to me. If I want to share the file, it doesn't stop me, but I wouldn't want to because then I would have to share my credit card number too
Non-intrusive, no ads, does not affect the useability of the file at all, but it does deter sharing...