Phizzy raised a good question in the opening post. But I am looking at the significance of the question from the opposite perspective of what I think Phizzy is looking at it. You see, to me the Bible (even the NT) has too many books in it. To me the Bible has books in it which never should have been included in it.
Several months ago I started thinking that the WT should adopt their own canon of the NT, one which excludes the books which NT critical scholars say are written under a false name (and that future WT revisions of the NWT should reflect that revised canon). For example, the WT should exclude the Letter of 2 Peter and the Letter to Titus.
In addition, the WT should exclude the letter of Jude and the book of Revelation and the book of Esther.
But the WT would never want to do any of those actions. But hypothetically, if the WT were to do such it would change the religion dramatically and it would be another way they could distinguish their religion from other religions of Christianity (religions which the WT claims are apostate). Making such changes would enable them to make their religion much more liberal, much less fundamentalist minded, and much less focused on the idea of Armageddon and of the idea of a God who will slaughter billions of people.
https://en.wikipedia.org/wiki/Forged_(book) says the following.
"New Testament books identified as forgeries by Ehrman
"
https://en.wikipedia.org/wiki/First_Epistle_of_Peter says the following.
'Although the text identifies Peter as its author, the language,
dating, style, and structure of this letter have led most scholars to
conclude that it is pseudonymous.[3][4][5] Many scholars argue that Peter was not the author of the letter because its writer appears to have had a formal education in rhetoric and philosophy, and an advanced knowledge of the Greek language,[6] none of which would be usual for a Galilean fisherman.
New Testament scholar Graham Stanton
rejects Petrine authorship because 1 Peter was most likely written
during the reign of Domitian in AD 81, which is when he believes
widespread Christian persecution began, which is long after the death of
Peter.[7][page needed]
More recent scholars such as Travis Williams say that the persecution
described does not appear to be describing official Roman persecutions
after Peter's death, thus not directly ruling out an early date for the
composition of the epistle.[8]
Another dating issue is the reference to "Babylon" in chapter 5
verse 13, generally agreed to be a claim the letter was written from
Rome. It is believed that the identification of Rome with Babylon, the
ancient enemy of the Jews, only came after the destruction of the Temple in AD 70.[9] Other scholars doubt Petrine authorship because they are convinced that 1 Peter is dependent on the Pauline epistles and thus was written after Paul the Apostle's ministry because it shares many of the same motifs espoused in Ephesians, Colossians, and the Pastoral Epistles.[10]
'