[17] That the man of God may be perfect, furnished to every good work.
Whether "profitable", "useful", or another word it certainly is good enough perfect the man of God.
AMEN!
Rome exhibits a basic misunderstanding of God's intent in giving us the Scriptures.
God has always spoken by His word. The Ten Commandments were written. The Old Testament was written. The New Testament was written. Men are conceptual beings and the written word is the way God has ordained to reach His children through the guidance of the Holy Spirit who renews our minds to understand the things of God.
Each of us who have been adopted by God from the beginning of time makes up the invisible church of Jesus Christ on earth. And the particular churches who are the members of the visible church of Jesus Christ on earth are mandated by God to follow His word in order to sanctify His family and bring them to repentance, obedience, faith and salvation.
Rome intrudes a false partition into that foundation which separates men according to their adherence to Rome's dictates, and not according to the instructions set down by God in the Bible.
But as Paul assures us...
"Nevertheless the foundation of God standeth sure, having this seal, The Lord knoweth them that are his." - 2 Timothy 2:19
The 25th chapter of the Westminster Confession of Faith teaches...
V. The purest Churches under heaven are subject both to mixture and error;[10] and some have so degenerated, as to become no Churches of Christ, but synagogues of Satan.[11] Nevertheless, there shall be always a Church on earth to worship God according to His will.[12]V. This catholic (universal) Church has been sometimes more, sometimes less visible.[8] And particular Churches, which are members thereof, are more or less pure, according as the doctrine of the Gospel is taught and embraced, ordinances administered, and public worship performed more or less purely in them.[9]
Because Rome does not teach and embrace the doctrine of the Gospel, but instead chooses to preach "another mediator" through "another gospel" by "another Christ," Rome does not "equip" its members adequately. As we've heard from RC apologists on this thread, Rome does not believe God's word to be "profitable" nor "useful" above all else. Instead, Rome elevates man-made traditions and the doctrines of men above the word of God, and thus, Rome stands outside the church of Christ on earth.
The verse says that the study of the scripture produces a perfect clergyman. But it does not say that the study of the scripture alone does that. In fact, the previous verse, verse 14 say that Timothy has to start with the knowledge he learned from St. Paul orally. "Profitable" or "useful" means that it is added on to something else, namely, the Holy Tradition of the Church.