“That is also true. The reason is because that is the Mesorah which we have recieved from R’ Shach, The Chazon Ish, The Chofetz Chaim, Rabbeinu Yitzchok Elchanan, R’ Akiva Eiger, The Noda B’yehuda, The Vilna Goan etc. etc.”
1) Why does the mesorah only start a few hundred years ago?
2) All/many/most of those you mention had a job. Is that now not part of the Yeshivish mesorah?
3) I would not include the Vilna Gaon. He was FOR secular learning.
4) One can very arguably make the statement that the Torah True Jews in the time of the Mikdash would be considered MO today. In addition, one can arguable state that the Rambam (and most likely most other Rishonim) would be considered MO.
5) The ones who changed mesorah can arguable be defined as Yeshivish and not the other way around.