Is it more meritocratic? Or do you use a different version of meritocracy from the person who coined the term? For instance, since you attack athletic skills, could you explain why you would consider the mental “muscle” above the others? Compared to the advantages given to for racial or SES issues, you seem to pick the one that is actually entirely … meritocratic! Unless you consider a mathlete superior to a pure athlete!
Do you really consider the ability to do “well” throughout high school and pick up enough math “knowledge” sufficient a metric? What if a school decided to judge students solely on the SAT test and make it free and easy for every student in the US to apply? How selective would such school be if 2,000,000 applicants fought for one of the 500 annual spots? Oops, we are now beyond your IIT (or IIM) range, aren’t we? Do not like the SAT? Let’s make it based on the GPA only. Same metrics and voila … again the most selective school on earth in terms of admissions?
What kind of class will such university have? The luck of the draw might yield enough people to throw a football or play a tune of two? Will everyone else be a CS or business major who could not present a cogent argument, or have much of general culture. Compound that for a few decades and let me know if a world that produces solely technical geniuses would be that great! A world filled with characters like the doctors on Bone?
Does the term “narrow” begin to be clear to you? I suggest you dig a bit deeper and read more about meritocracy before tossing the term around.