Judging by the excuses given in the post, I'm going to guess that 'stress' is the answer. It sounds like a crazy place to work, even if it's making money. It could very well be that everyone decided to quit, and so it just dissolved.
It seems unlikely that an entire company would disband simply due to stress.
Nope, no one quit - the core team is now on other products in the company. Check back for parts 2 and beyond for updates, great lessons learned.