First, we need an actual meritocracy --- the purest forms of that I've ever experienced were when in the military when in a unit with an officer who both had good ethics _and_ a good understanding the people under his command, and a school system which I briefly attended when I was very young --- my understanding of the school system based on my recollection and how it was explained to me by my parents in the light of more typical schools was that classes were divided between social and academic: academic classes (English and other languages, math, science) were attended at one's ability level, with a four year cap through eighth grade (after which the cap was removed) and social classes (homeroom, social studies, physical education, home economics and shop class) were attended at one's age level. In addition to grades K--12, many of the teachers were accredited as faculty at a local college, and if need be, students were either transported to that college, or professors from the college would come to the school to teach classes. It was not uncommon for students to graduate from high school and simultaneously be awarded a college diploma.
the problem with meritocracy in the military is that it is defined top-down. iaw, there is an in-group that decided who gets to join them.
a better approach would be what i have seen in the boy scouts of america a few decades ago with regards to joining the order of the arrow. there the whole troop would select those who would be invited. most troop members were not members of the OA themselves. thus the ones who were already selected had little influence in who got to join them.