There is no pretense. What some may not understand is that the Orthodox, Catholic, and Coptic churches are united with one another and that the foundation of each is through Christ and the Apostles. Parishioners of any of these three can take part in the worship of the others. It is going much to slowly, but unification between Catholic and Orthodox is being worked through, and is already fact between Catholic and Coptic. There are no great divisions in these three Churches.
Now, let's take other Christian denominations that broke away from any of the above three to follow someone else: Martin Luther, John Calvin, Joseph Smith, Henry VIII, etc. Not only did these break away from Catholic/Orthodox/Coptic churches, they broke away from the Sacraments and from Apostolic Traditions and Early Church practices.
Ask yourself, why come down so harshly on the Catholic Church without being equally harsh on the Orthodox and Coptic Churches? You have no more agreement with them about Sacraments, Traditions, and Early Church teachings that you do with Catholics. If you do agree with Orthodox and Coptic churches, then you are in agreement with the Catholic Church. We three stand together when it comes to Scripture, Traditions, Sacraments. We three work together towards greater unification. Which of the three are Protestants working with?
To sum up: The Catholic faith believes the Orthodox and Coptic Churches rightfully proclaim they were founded by Christ and the Apostles.