I agree that barrel break in is not necessary. The people who make barrels like Shilen, Lilja, Schneider, Obermeyer, Kreiger and so on know how to put exactly the kind of finish in the throat, and barrel that they think works best.
It would be incredibly arrogant for someone like me to think that I can do a better job finishing out their barrels (by break in) than they can. If they thought a barrel would shoot better by having something else done to it, they would have already done it. Otherwise, people like myself would buy barrels from barrel makers who DO finish their barrels so they shoot good from the start.