Lemme get this straight...
They make the game always online with no option to play local, then limit the number of times you can reset the level (start a new game), which you would be doing to farm items to face the higher difficulty levels, because their server infrastructure can't keep up with the demand...
BUY MORE F#CKING SERVERS YOU USELESS ASSHOLES
Seriously, if they're making it compulsory to play on their servers, they should have enough headroom for you to start the game as many times as you like.
And for all those who would leap to Blizz's defense and waffle on about how they don't want to overprovision etc, f#ck em. They wouldn't need anywhere near as much infrastructure if there was a local version of the game for people who wanted to play singleplayer/non-bnet MP.