I would say that it's because of all the bands that have ever existed, almost all of them are broken up, so it's gonna happen eventually.
I was really sad when Blood Brothers broke up. I saw them last year on Halloween, playing with Trail of Dead. It was fucking brilliant. But I had listened to them for awhile. I got all excited when I first heard Failure and it was at my friend's house, so he had the dubious pleasure of telling me they'd broken up. Also...At the Drive-In, Beulah, Elliott Smith (sorta), Mclusky, Guided by Voices, the Unicorns, The Jesus Lizard, Kyuss, probably lots more.