It’s likely b/c you need to list the school as your first-choice so that the school knows that you’ve basically committed to attend them (b/c if you get a college-sponsored scholarship by listing a sponsoring school as your first-choice and decide to go elsewhere, you won’t get another scholarship from NMSC and probably can’t call yourself a “SCHOLAR” anymore,) as they’re allocating NM scholarship funds based on the number of students who will ACTUALLY attend and cannot afford to keep that much money on the back burner while students change their minds.
NMSC publishes an “annual report” (the latest I can find is for 2017 so not really annual lol) listing the schools with the highest number of National Merit Scholars (not first-choice, and not necessarily a school-sponsored scholarship either, as a lot of students receiving NM $2500 or corporate scholarships go to non-NM scholarship offering schools, such as the Ivies.) So yes, there is some glory to enrolling a high number of NMS, especially for large state schools like UCF or Alabama, as it’s a way to attract high-stats students who may have went to a more “prestigious” schools w/o the merit scholarship offer. For schools like the T20s that already attract a lot of similar students, it’s not really necessary for most of them to offer scholarship funding: they usually have robust FA programs and enough qualified students wanting to attend w/o having to look at NMS in particular.
Hope that helps! Good luck with admissions!