If someone was trying to set up a completely new installation of NIS, that would certainly be misguided. Pointing new devices at an existing NIS infrastructure is another matter though: most of the people in this situation don't really have a choice in the matter, usually for reasons of budget or management restriction.
Even though it's less than ideal to point new devices at old infrastructure such as this (it adds to the technical debt of the larger problem), the questions are reasonable ones and there is no reason to turn them aside.
(In hindsight, I apologize for my misguided question.)