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.
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.
It seems unlikely that an entire company would disband simply due to stress.