They don’t have too, but the point is that our understanding of Church is similar in that there is one true Church of Christ, which teaches one baptism, one faith. . . etc. Here is a wonderful quote from St. Irenaeus of Lyons:
"Indeed, the Church, though scattered throughout the whole world, even to the ends of the earth, having received the faith from the apostles and their disciples. . . guards [this preaching and faith] with care, as dwelling in but a single house, and similarly believes as if having but one soul and a single heart, and preaches, teaches, and hands on this faith with the unanimous voice, as if possessing only one mouth."