To say the Dead Sea Scrolls were "not allowed in the Bible" is a bit of a mix up. The DSS contain copies of every book from the Old Testament except Esther, among many other works. Some of the scrolls are rather mundane descriptions of daily life in the Essene community. They represent something more like a library than a collection of canonical books.
Also, the DSS disappeared before the New Testament canon was compiled. No one knew of the DSS from the time they were hidden in about 70 AD until they were discovered in 1947 - 1948.
Enoch was rejected by both Jewish and Christian authorities as being canonical; this despite the fact that it is clearly quoted by both Peter and Jude and Paul appears to may an allusion to it in
1 Corinthians 11 - though that point is contested.
The book was accepted by many in the first couple of centuries of the church age. Origin, Irenaeus, the pseudographical Epistle of Barnabas, Justin Martyr and Clement of Alexandria all quote from it. Tertullian calls it "holy scripture."
The first problem with the book is that it is manifestly not the work of the Biblical Enoch (
Genesis 5:22-24). It is a type of work called pseudographical. It claims to be written by Enoch but we know that it was really written in the 2nd century BC. The biggest problem theologians in the 2nd century AD and onward had was with the activity of the fallen angels described in the book. This is probably the primary reason it was later rejected from the official canons.