> sometimes it's non-trivial (and possibly NDA violating) to describe why the recommended solution isn't feasible.

It's not just NDAs. A lot of times people are constrained in what they can do for a reason they're not inclined to admit. This is extremely common with office politics or any kind of corruption.

The boss demands X because Y would mean not getting kickbacks from a particular vendor, but she can't tell you this so she has to make up some hogwash. Now you have to go ask someone how to do X, and you know the boss's justification is ridiculous but you also know that you can't list "because the boss has issued a rattlebrained mandate" as the reason in a written communication with your name attached to it, so you have to submit the hogwash as the reason or make up your own.

Then the person answering the question points out that the proffered reason for doing it is absurd, which everybody already knows, but nobody can admit it.

In large organizations this kind of thing happens so often that people become conditioned to not even question it and just follow orders, and then it happens even when there isn't a hidden underlying reason, because there is now a culture of not questioning stupid decisions.

And even when you can explain your whole justification for doing Y, it often doesn't help. In my experience, longer your question is, the more likely it is that people will just skim over it and misunderstand it. Or they'll argue against your reasons for doing Y and try to convince you that you really should be doing X anyway.