One of the criticisms of Dead Sea Scrolls is that Dead Sea Scrolls are not reliable in terms of antiquity. The authorship of Dead Sea Scrolls is usually credited to Essenes sect. The Essenes were famous for their continuing use of old, worn materials, as shown by Josephus in Jewish Wars Book 2.
For Example, The Essenes replace neither clothes nor footwear until the old set is ripped all over or worn through with age (Jewish Wars Book 2, 126).
This would mean that Essenes held that an ancient parchment, manufactured many years before, was venerable and suited for the recording of their inspired writings. The date of manufacture could be 100 years or more before the date of composition of the contents. It is quite fallacious to say that the date of composition was the same as the date of manufacture.