This might be a large part of the reason.
Catholics really do think their sanctification is by means of the Church, through its ministry and sacraments, as St. Irenaeus wrote:
“We receive our faith from the Church and keep it safe; and it is as it were a precious deposit stored in a fine vessel, ever renewing its vitality through the Spirit of God, and causing the renewal of the vessel in which it is stored. For this gift of God has been entrusted to the Church, as the breath of life to created man, to the end that all members by receiving it should be made alive. And herein has been bestowed upon us our means of communion with Christ, namely the Holy Spirit, the pledge of immortality, the strengthening of our faith, the ladder by which we ascend to God. For the Apostle says, ‘God has set up in the Church Apostles, prophets, teachers’ [1 Cor. 12:28] and all the other means of the Spirit’s working. But they have no share in this Spirit who do not join in the activity of the Church...."
"For where the Church is, there is the Spirit of God; and where the Spirit of God is, there is the Church and every kind of grace. The Spirit is truth. Therefore, those who have no share in the Spirit are not nourished and given life at their mother’s breast; nor do they enjoy the sparkling fountain that issues from the body of Christ.”
Catholics really do think their sanctification is by means of the Church, through its ministry and sacraments, as St. Irenaeus wrote:
“We receive our faith from the Church and keep it safe; and it is as it were a precious deposit stored in a fine vessel, ever renewing its vitality through the Spirit of God, and causing the renewal of the vessel in which it is stored. For this gift of God has been entrusted to the Church, as the breath of life to created man, to the end that all members by receiving it should be made alive. And herein has been bestowed upon us our means of communion with Christ, namely the Holy Spirit, the pledge of immortality, the strengthening of our faith, the ladder by which we ascend to God. For the Apostle says, ‘God has set up in the Church Apostles, prophets, teachers’ [1 Cor. 12:28] and all the other means of the Spirit’s working. But they have no share in this Spirit who do not join in the activity of the Church...."
"For where the Church is, there is the Spirit of God; and where the Spirit of God is, there is the Church and every kind of grace. The Spirit is truth. Therefore, those who have no share in the Spirit are not nourished and given life at their mother’s breast; nor do they enjoy the sparkling fountain that issues from the body of Christ.”