Nomesorah; “the top” boys in all of the yeshivos you mentioned were the products of MO yeshivos? Have you taken a poll? on what are you basing this statement? Having gone to a few of the places you mentioned, it is true that there are some boys there went to MO schools(myself included), but the overwhelming majority, 95-98%, did not. It’s not as if the MO school built them up to being bnei torah through modern orthodoxy, and then they went on to the next natural step to Lakewood. It was despite their background that they ended up there, often resulting in being ostracized from friends and even family.
As someone who went through the MO system, the schools are not interested in producing bnei torah, or even very committed jews; they’re interested in producing proud, educated, PHd -holding tax paying zionists who hopefully keep shabbos and wear fabric on their heads, (unless said tax paying position makes that uncomfortable)and make enough money to send their kids to the same enriched institutions(my own school is not enriched). There are some rebbeim in modern schools (again, myself included) who are trying their best to teach authentic torah in a maelstrom of heresy and bizayon hatorah, but that’s not the undercurrent students experience, not among faculty, home life, and definitely not among their social peers. We grew up making fun of “black hatters” and “those fanatics who won’t hug their aunts” or who won’t watch television.
Learning nach and feeling better about themselves, that they know something that the bnei yeshivos do not know, is just part of the lie that they’re sold. I learned nach in yeshiva; I later learned that I had been fed lies and been given a narrative around tanach that had no mesorah and was better suited for a bible class given by david Ben gurion. So yea, I think MO schools learning navi is a chisaron, not chas veshalom because of nach itself, but because of both how they learn it and the superiority it engenders over those who don’t.