The problem with pure merit based is that there are too many kids at the top. Too many perfect SAT scores and perfect GPAs. "Anybody" (not really anybody) who tries hard enough can get perfect scores and perfect grades. Then the schools have to do "holistic" admissions which aren't really holistic because it's only after you pass the bar for test scores and GPA that your other activities are looked at.

That is what the media want you to think happens but were that true then average SAT scores at US colleges ex(Caltech and MIT) would be a lot higher than they actually are.

The official line seems to be ‘with so many perfect scores we need to practice holistic admissions to get the creme de la creme’ but the actual scores of undergraduates admitted are sometimes far from perfect which leaves me unconvinced that they are telling the truth.
Become what you are