Question

Can someone who studied Torah on his own—sat and learned the entire Talmud, Maimonides, Tur, Beit Yosef, Shulchan Arukh with all the commentaries, and all of the Chazon Ish word for word—and who is also socially engaged and exceptionally wise, but never learned with a rabbi and never discussed Torah topics with a study partner or students, but simply sat and learned; and you could even test him on everything he learned and he would get a perfect score—is he lacking something? Can one say that he would issue halakhic rulings and offer reasoning in an incorrect way? Is there some fundamental element that gets transmitted through speech and living alongside a great scholar, and that it is impossible or very, very hard to derive just from simply learning everything that is written?
Thank you very much for the explanation