There are a limited number of mandates that can come from the top. Upper management loses credibility when they issue endless mandates, even if all of the mandates are reasonable.
It’s also unrealistic that everyone underneath can focus on many mandates at once. Which leads to the loss of credibility when mandates start getting ignored out of necessity.
Yes, for any specific mandate like this, it could easily be accomplished. The point is that in aggregate there are too many of these to accomplish. Competent management will choose the highest value things to focus on. This isn’t defeatism. This is realism. Focusing on everything is the same as focusing on nothing.
Realistically, mandating RESTful APIs at the exec level is unlikely to be a big win for Microsoft. The teams working on APIs at scale are largely already doing this (and you’ll notice multiple groups represented by the authors). The teams that aren’t doing this are largely not building APIs that benefit a great deal from RESTful APIs, because they’re building internal APIs or similar and RESTfulness would be nice to have but not particularly impactful.
It’s also unrealistic that everyone underneath can focus on many mandates at once. Which leads to the loss of credibility when mandates start getting ignored out of necessity.