"Most" horror stories, sure, but not all. I've heard more than enough where the cause seems to be that somebody did a chargeback or other things that were out of control of the company in question. There was one particular case a few years ago, where a sudden burst in volume seems to have triggered it.

Bottom line is, its a huge risk. I wouldn't want to base my business on such a significant risk and at least have a fallback in place.