I'm sure there are other examples, but you picked one here that is very unfair.

> their new computer. The computer had no songs on it and the Zune synced with that machine and wiped all the existing music

This is identical to the default way the iPod worked. If you bought a new Mac, and needed to get your music onto it, you had to use the migration assistant (connect via ethernet or firewire) or copy the music yourself. If you just plugged in your iPod to the new 'empty' mac and hit Sync, you'd lose your music too.

This was done as a show of good faith to the RIAA - their nightmare was that users would go from one dorm room to the next, dumping all their music onto all their friends' PCs. As a result, an iPod (or indeed still an iPhone today) can only sync with one music library (aka one computer) at a time. If you put it in "manually manage" mode, you can copy onto the iPod/iPhone from a 'foreign' library, but you can still never copy in the other direction. And all of this is true even when your music has no DRM encryption.