With "...I have known..." being the key phrase.
For me, the vast majority of practicing, Bible-educated, disciples of God's Word who I know, have at least a basic understanding of the importance of the entirety of the Bible - including the Old and New Testaments. Disciples of the Word know that Jesus Christ and God's plan for redemption is the principle theme of all the Bible.
I have never been to a church where the OT was not taught from. Where do these ideas come from?