To suggest that human fallibility among individual Catholics undermines the Church’s position is to misunderstand Catholic ecclesiology. The Catholic Church fully recognizes that individual believers, even saints, scholars, and popes, can err in their private theological opinions or personal judgments. This is precisely why the Church differentiates between the private views of individuals and the official exercise of magisterial authority.
Aside from the self-evident logic flaws in this statement, it is an anti-scriptural viewpoint. The faults of Popes and others representing the Catholic sect present an eras long history of ill considered doctrine and moral and ethical failure. By their fruits they are recognized as other than the faithful Christians they should be. They are the organization. These aren't just "hidden reefs at your love feasts." They are the Catholic organization. The moral ills of the past are striking, but more importantly they continue. The Catholic sect is characterized by moral failure, more wide-spread and more pronounced that anything present among Witnesses or most Protestant sects.
Appealing to the age of Romanism is a false argument. The Bible says Satan is extremely ancient. That does not make him holy, God ordained, or any such thing. The argument from age is misdirected.
You cannot separate the sins of the popes and clergy from the identity of the church. There is no mythical, or mystic, separate identity. The Church is the sum of its authority structure now and in past ages. The Roman sects history is dark. It continues to be so.