Offerings are for the benefit of the Church...

They themselves should remember that riches have been given to bishops as alms for the administration and advantage of the churches. As the rule says, "The benefit is given because of the office." Therefore, they cannot with a good conscience possess these alms and defraud the Church.  The Church has need of this money to support ministers, aid education, care for the poor, and establish courts, especially for marriage   So great is the variety and extent of marriage controversies that there is need for a special court, for which the endowments of the church are needed.  Peter predicted that there would be godless bishops who would abuse the alms of the Church for luxury and neglect the ministry.  Therefore, let those who defraud the Church know that they will pay God the penalty for this crime.
~BOC, PPP, 79-82

The authority to administer the Gospel lies with the Church....

Wherever the Church is, there is the authority to administer the Gospel.  Therefore, it is necessary for the Church to retain the authority to call, elect, and ordain ministers.  This authority is a gift that in reality is given to the Church.  No human power can take this gift away from the Church.  As Paul testifies to the Ephesians, when "He ascended...He gave gifts to men" (Ephesians 4:8).  He lists among the gifts specifically belonging to the church "pastors and teachers" (4:11), and adds that they are given for the ministry, "for the building up of the body of Christ" (4:12).  So wherever there is a True Church, the right to elect and ordain ministers necessarily exists.  In the same way, in a case of necessity even a layman absolves and becomes the minister and pastor of another.  Augustine tells the story of two Christians in a ship, one of whom baptized the catechumen, who after Baptism then absolved the baptizer.
~BOC, PPP, 67