Ok, I think Iām still on topic. The OP wanted reasons why weāre not Catholic (in my case, anymore), and thatās what Iām doing. I donāt mean to go off-topic, so forgive me if I am.
I think it should rather be said that the Catholic Church St. Ignatius of Antioch is referring to was not the Church Cardinal Humbert was creating. At that point in time I wouldnāt want to say, definitively, that the two were separate. Perhaps they were though, as the Bull had already been slammed upon the altar of the Hagia Sophia. Iām not sure at which point, definitively, the one became two, but it was not long after that, and has definitely happened at the points where Papal Infallibility and Universality became dogma.
To double check I re-read through my copy of the letters of St. Ignatius on his way to being martyred. Nowhere does he instruct others to be subject to the Bishop of Rome, but to their own bishop. He never says that the Church is incomplete without the Pope, but that itās Catholicity resides in the laity, the deacons, the presbyters, and the bishop together. That is Catholic, the universality, the āwholeness and completenessā. We require nobody to be part of the Body of Christ for that body to be complete. His ecclesiology seems to be one of collegiality and community, as is the Orthodox structure to this day, not monarchy, as Roman Catholicism is.