What I failed to realize until I read this article is that online mode means multiplayer mode, even for the single player campaign.
There's a vast difference between that and merely being connected at all times - Assassin's Creed 2 also had a redicilous stay-online-at-all-times system, but it didn't have any crazy restrictions in addition to having to stay online.
Online mode in Diablo 3 works exactly like online mode in Diablo and Diablo 2.
*EDIT* Ok, the game WILL eventually log you out if you're idle for too long.
Well, except that Diablo didn't have checkpoints - and you had to do a lot more backtracking to get to your last position if you logged out.
A LOT of people played Diablo and Diablo 2 alone on Battle.net - just to be part of the potential trading community and to have access to the gear exclusive to that mode. I, personally, played a lot of characters online without ever joining up with anyone.
The only change is that you have to be online with Diablo 3 - and that you can't play offline.
That's what I'm saying is old news, and don't understand the "new" reaction.
It's as if people just don't remember how Diablo and Diablo 2 worked.
True, but they didn't log you out because you had to take a phonecall or answer the door.
Well, I honestly don't remember if you could be logged in indefinitely.
But, I generally don't take long to answer a phonecall or the door.
I haven't played the beta personally, but I'm pretty sure Blizzard will not want people to be punished for doing such things.
I'd be surprised if you didn't get, at least, 15 minutes before a log-out happens.
If that's REALLY such a realistic concern, then I guess I'm just surprised.