What's Beef: Twitter

Can someone explain to me why this is the new Beef spot. Like celebs don't run to their blogs anyone but run to twitter. The most recent examples are Alicia Keys, Swizz Beat's Wife, Bow Wow. I think its more of an impulse beef. Like I think if they had more tyme to think about them being mad, or got a chance to talk to their PR or sumthing, they wouldn't tweet it. But on the other hand, sites that have status update are probably for this exact type of thing...