It's nowhere near simple.
Is it possible for a top-flight athlete to be on academic scholarship and not count against NCAA numerical limitations? Sure, but it's not something that can be done by snapping one's fingers. The amount of merit-base financial aid is not all that great and an award that's equivalent to a full ride is rare (covering full tuition isn't that isn't that uncommon in the merit aid universe, but a grant including room, board, and other sundries is). Further, it's not as if admissions officers coming across students with great academic credentials can wave a magic wand a create merit awards for them. Those grants come from established, funded programs, a many of them have requirements that go beyond academics e.g. being from a certain geographic area, an alumnus of a particular high school, a first-in-the-family college attendee, enrollment in a particular division of the college, gender, ethnic origin, etc. In many cases a university officer will refer a potential recipient to the committee that decides on the award. In as many, if not more, the onus is on the student to be aware of the award's existence and apply for it.
Bottom line is that if an athlete is receiving only merit aid it had better be from an established program within the university that grants it to a broader base (beyond athletes) of students and the athlete better have the credentials to win it, because it's going to send up a red flag.