Did they need them? They were able to study the Scriptures, as the Bible says, (the Old Testament happens to be Scripture also), and verify a New Testament message using the Old Testament.
Yes, the OT is scripture; however, they could only use the OT prophecies about the coming Messiah to study what Paul was telling them had been fulfilled, but they couldn't use the scriptures to verify the miracles that Paul conveyed.
When I was growing up, we were taught the doctrine of "Sola Scripture" and we don't believe it if it's not in the Bible. Also, we are silent where the scriptures are silent. Really? What about impossing your own belief?
Well, let's take a look at a few of these.
1. Infant Baptism - although it is not specifically written out, there are plenty of passages that elude to it. The Baptist church rejected infant Baptism based on the assumption that there were not any infants where passages state "whole household" was baptized. Here they are adding their own belief to the scripture and state that the scripture is silent.
2. Women not wearing pants - this is not forbidden in the Bible. They use the passage that women should be modest to back up their belief. So, from the time I was in elementary school up through the 8th grade, we were not allowed to wear pants to church activities. Yeah, those cullocks (sp?)with the big baggy leg holes where sure modest. Not! Whenever we went horseback riding, the boys wanted to help the girls get on their horse so they could get a peek. Let's not forget how after you sat down, the cullocks bunched up around your upper thigh and you were giving the boys an eye full. How about playing softball in those things and sliding into home plate showing your unmentionables off to God and everyone else. When I was in 9th grade, the church decided to do away with cullocks and said that the girls could wear loose fitting pants to youth group activities.
3. Movies - couldn't go. Where in the Bible is this found? I couldn't go with my little neighborhood friends to see Snow White, Dumbo, Lady & The Tramp, Mary Poppins, Sound of Music, etc. I never saw these movies until I was 24 and then it was on VHS when I bought them for my daughter.
4. Dancing - forbidden. Kind of reminds me of Footloose. However, the Bible does mention in several places in the OT where dancing was not forbidden, even a time to dance. Whenever I would ask about this, I was told that the NT was our standard of living, so since it wasn't in the NT it was a sin. (Whatever)