You may be right on percentages but you are missing a bigger picture here. I know the numbers but to break it down simply think of it this way:

If Harvard admits 100 students BYU admits 360.

If you compared the 100 admitted at Harvard and the top 100 at BYU you would not notice any difference on merit based application criteria and frankly BYU might actually be better.

Further, BYU deals with a pre-selection bias of people applying.

Lastly, I believe BYU actually has a higher matriculation rate than Harvard does, which is impressive.

So I don't know where you got your numbers, I don't think they are exactly correct, they give a false impression of what is really going on.