I think we take issue with requiring the leap to Microsoft “deliberately” obstructing interoperability. Microsoft just isn’t incentivized to make it simple to implement, but it’s probably less complicated than the various web standards.

An engineering team in Microsoft decides to switch from binary format to XML to save effort in the long run; even though it'll take some effort now, they have the competency, and can afford it. They are absolutely correct!

But then their manager needs to sell this project to the higher-ups, who have read BillG's memo about how "One thing we have got to change in our strategy – allowing Office documents to be rendered very well by other people's browsers is one of the most destructive things we could do to the company. We have to stop putting any effort into this and make sure that Office documents very well depend on proprietary IE capabilities. Anything else is suicide for our platform. This is a case where Office has to avoid doing something to destroy Windows." and took it to heart. So what does he do? Why, he spins a tale that since it's XML, they'll be able to standardize it, and everyone else will still be forced to interoperate with MS Office anyhow, because it will be the de-facto reference implementation (by the virtue of being there first, and widely deployed), and the spec is going to be an absolute PITA to implement decently — and that manager too will be absolutely correct!