they were as generous as Harvard is about pushing application numbers, you would see that percentage go way down from 65%.

Clearly Harvard is more selective.  But a better comparison would be people who have a reasonable shot of getting into Harvard, only those people applying, versus the similar group for BYU.  Harvard might be closer to 20% in that case, while BYU might drop to 30%.  This is as explained to me by one of the famed Elec Eng professors at the Y once before, and he had spent quite a time in admissions strategies and policies for the Y.  Take it FWIW.