The short answer is, because it is no authority to you, and would not define the Catholic views with precision as the Catechism does.
Off the top of my head, among the Deuterocanonicals we find the clearest textproof for prayers for the dead (for the Purgatiory itself we are fine with 1 Corinthians 3), the freedom of will (Sirach 15:14), the concept of the communion of saints, guardian angel, demonic possession and exorcism in Tobias.
I believe Tobias played an important part in the conversion of my wife, who, as a former Protestant, was rather familiar with scripture but had never read it. I knew that it must have had quite an effect on her when I noticed her crying while she was reading it.Although it is a rather short story, is crucially important to our faith in so many ways. It is the only place in scripture where the Archangel Raphael is mentioned. We also see the earliest scriptural account of a man performing an exorcism. The book of Tobias shows clearly how heavenly beings hear the prayers of the faithful on earth and will petition God on our behalf. The coming of Christ is prophesized by Tobias the elder. It teaches how good works play a part in our salvation, and how prayer, fasting and almsgiving can bring redemption. The book of Tobias also imparts the Catholic concept of the guardian angel.
How the Protestants could have, without any authority whatsoever, removed this beautiful and revealing work from their scripture is as mind boggling as it is criminal.
Yeah, but you all quote from the Fathers all the time, which is fine, but you know they would carry as much weight with us (in terms of authority) as the Deuterocanonicals.
Off the top of my head, among the Deuterocanonicals we find the clearest textproof for prayers for the dead (for the Purgatiory itself we are fine with 1 Corinthians 3), the freedom of will (Sirach 15:14), the concept of the communion of saints, guardian angel, demonic possession and exorcism in Tobias.
I didn't know that, Alex. Thanks.