Yes, likewise the sacraments exist only in and through the Catholic Church. Yet, Orthodox sacraments are valid. The Orthodox Churches, by virtue of apostolic succession, retain an IMPERFECT union with the Catholic Church. Protestants, by virtue of their baptisms, have an imperfect communion with the Church as individuals. The Orthodox are imperfectly united to the Church as particular CHURCHES. That’s the fundamental difference.
It’s not always as black and white as we would like to think. For example, most date the schism at 1054. What of Antioch (Greek, not Syriac)? They remained in communion with both Constantinople and Rome for many decades after the schism between Rome and Constantinople… so on what date did their bishops lose jurisdiction?