It seems that God has indeed designed that the inspired Word of the Bible become uniquely powerful by passing through a Spirit-filled person on the way to make a dead heart live.
Since, in the wisdom of God, the world did not know God through wisdom, it pleased God through the folly of what we preach to save those who believe. (1 Corinthians 1:21)
One reason for this is that the saving Word is gospel, that is, news. News is to be heralded. The news-quality is captured in the kind of speaking that announces, declares, proclaims, heralds, exults over the truth of what God has done in Christ.
Here is Spurgeon’s tribute to the power of “the preached Word.”
Personally, I have to bless God for many good books…but my gratitude most of all is due to God, not for books, but for the preached Word—and that too addressed to me by a poor, uneducated man, a man who had never received any training for the ministry, and probably will never be heard of in this life, a man engaged in business, no doubt of a humble kind, during the week, but who had just enough of grace to say on the Sabbath, “Look unto Me, and be saved, all the ends of the earth.”
The books were good, but the man was better. The revealed Word awakened me, but it was the preached Word that saved me; and I must ever attach peculiar value to the hearing of the truth, for by it I received the joy and peace in which my soul delights.