"Escalating and unanticipated requirements, especially without added budget to meet those requirements, can have devastating effects on both a project and the larger software company."
No, this is not it at all. What this should say is:
"The customer (Microsoft) will always demand more than is agreed to, while simultaneously refusing to pay for it, and expect the vendor (Dark Side) to foot all of the expenses to meet the additional demands."
Big companies will dangle a huge carrot (or suitcase full of money) in front of a bunch of 20-somethings and their startup company to get them salivating, and almost every time those 20-somethings will chomp at it without questioning motives, analyzing risk, or even having a lawyer look at the proposed contract.
It wasn't mission creep. Mission creep is when the mission changes unexpectedly. Microsoft knew damn well what they were doing, and intended to exploit Dark Side for free work product. Maybe MS didn't anticipate them imploding like they did, but it likely didn't matter to them since they no doubt retained ownership of all of the work product anyway, which they could hand off to another firm to finish, or implode trying.
Honestly I don't see why anyone would do business with Microsoft, or any other huge, publicly-traded bureaucracy for that matter.