CT,
“We might even be able to say gedolim achieved what they did despite the Yeshiva system not because of it.”
How many can you count. I think the list finishes there. As all Gedolim past hundred years plus have learned in a Yeshiva, may it be Volozhin, Mir, Solobodka/Chevron, etc and later Brisk..
I think many of the great Rosh Yeshivos in America have learnt in Brisk.
Brisk does have something unique; they study Kodeshim, and its Gemora’s without any Rishonim and barely any Achronim. You basically learn how to study yourself from scratch. i.e. starting from the pesukim Toras Kohanim Gemorah Rambam with the full hekef..