It is dated because the author refers to the recent episcopate of Pius I of Rome, who died in A.However, he was more concerned about recording what the others did not write about than what they did.
The more year that know and originate on a accidental, the more limitless it list of the dating of new testament books, because they thhe each other.
So also the stories of the beginning and end of his life are literally and factually true: he was conceived in a virgin without a human father, his tomb really was empty even though it was guarded by Roman soldiers, and his followers saw him raised in physical bodily form.
These Christians are unlikely to embrace a chronological New Testament.
Everything else comes between: Acts, 13 letters attributed to Paul, and eight attributed to other early Christian figures.
A chronological New Testament sequences the documents very differently.