I think it's more likely Microsoft knew and didn't care. The parent to your comment - by mhw - is pretty darned close. At Microsoft, legal and engineering are

I think it's more likely Microsoft knew and didn't care. The parent to your comment - by mhw - is pretty darned close. At Microsoft, legal and engineering are in different silos and don't talk to each other, except through senior management with limited bandwidth and legal/engineering understanding and also - in my experience, and to some extent - program managers. Developers (at least) are told not to look at patents or patent applications. I'd be surprised if PMs were told differently. Does MS Legal have engineers on staff to determine if something is worthy of a patent and to look for prior art? That's a possibility. But your "more likely" (granted - it's your opinion) doesn't seem incredibly likely (in my opinion.)