spotify caved in to pressure some months back and allowed people to sign up without going thru facebook - but a year go the only way to do that was to sign up at the german site via a proxy.
there's a growing trend of "sign up / sign in via your facebook identity" - e.g. goodreads does it now. [ luckily one of my pet cockatiels has a facebook account which I borrow for such occasions, as I refuse to have one of my own
]
I assure you that buying an amazon MP3 leads to a promotion for amazon cloud storage, but we are drifting way off topic now...
lets just say:
Sony readers: no ads, no nags, ever
Kindles: some imposed social media prompts,( at end of books) but not at all troublesome to most of their users. option to pay less for the hardware in exchange for accepting screen saver ads.