The top 10 percent policy is a merit based system and the most recent flavor of "progressivism" says that merit based systems are racist and should be abolished. Lottery and quota based admissions is what considered progressive today.
Lottery systems with an initial cutoff make sense if you have a large surplus of applicants who surpass your lower quality threshold. Rather than make asinine minuscule decisions over who exactly the top 1,526 out of 10,000 are, cull the 7,234 that don’t make the cut and randomly select from the survivors.
I'd rather prefer my surgeon, should I ever need one, be one of those "asinine miniscule" top 1526 applicants selected based on pure merit.
The entire point is that you set the initial cutoff such that the differences in “pure merit” between your threshold and the lowest candidate if you went anal-retentive on ranking do not translate into meaningfully different outcomes.