IIRC it was in response to many government sources requiring open formats (a good instinct) so just because they did it doesn’t mean they wanted to. They may have been forced to, and done the minimum as a result.

I believe it was the antitrust lawsuits that forced them too, and it shows; if you look at all the MS protocol/format documents and compare them to something like RFCs and ITU/IEEE/ANSI standards, the MS docs are noticeably harder to read with their verbosity, weird syntax notations and conventions, and almost look as if they were deliberately obfuscated.