Why do 21st century Protestants still not include the deuterocanonical books in the canon?

Given the Protestant motto [*semper reformanda*](https://www.thegospelcoalition.org/blogs/kevin-deyoung/semper-reformanda/) and the doctrine of *sola scriptura* which in essence strives to purify Christian teaching to be based only on the Word of God interpreted through the lens of the 12 apostles, **what is preventing Protestants today from including the Catholic deuterocanonical books *back* into the canon** when it can be shown: 1. How the NT writers [**did** make allusions](https://christianity.stackexchange.com/a/6319/10672) to those books 2. How recent research showed how the [NT writers relied on the Septuagint's version of the underlying Hebrew OT vs. the Masoretic text](https://theorthodoxlife.wordpress.com/2012/03/12/masoretic-text-vs-original-hebrew/) 3. Appeal to what Judaism itself consider as canon (i.e. 39 books) is irrelevant because Christianity should have its own hermeneutic, especially when the Septuagint text could be shown as less tainted by errors now. 4. How the two highly voted answers for the question ["Why were Deuterocanonical books rejected in the Reformation?"](https://christianity.stackexchange.com/questions/3189/why-were-deuterocanonical-books-rejected-in-the-reformation) fails to show a good reason for their exclusion from the Protestant canon because none of the reasons mentioned are derived from *sola scriptura*: - Luther and Calvin were motivated to either diminish or eliminate the deuterocanonical books to exclude scriptural support for Catholic doctrines - Appeal to St. Jerome's concern of the reliability of Septuagint has since been reversed after the discovery of the dead sea scrolls (see 2nd point above) - Synod decision post Luther & Calvin should in principle be re-evaluated when the apostles can be shown to rely on Septuagint more than what was known 400-500 years ago 500 years have passed since the violent and emotional schism. Both the Protestant and Catholic sides, especially in the academia, have since understood each other much better and became much less polemical. In the past 100 years the trend for both sides is to dig deeper into each NT author's 2nd temple Judaism worldview to better inform our understanding of the NT books, which is clearly **also** in the spirit of *sola scriptura*. Of course, one obvious reason is because the Catholic church had developed doctrines unacceptable to Protestants based on those books, like Purgatory, indulgences, etc. But if Protestants use proper hermeneutic to guard against "overzealous" interpretation of those deuterocanonical books (such as by controlling interpretation to what only the 12 apostles taught in the 27 NT books), why not include them in the canon? What makes this question different from previous questions such as [this one](https://christianity.stackexchange.com/questions/3189/why-were-deuterocanonical-books-rejected-in-the-reformation) is the **21st century context** because in principle Protestants are not bound by past decisions (per *semper reformanda* principle), but bound only by what the NT authors taught (*sola scriptura*). Therefore, my question asks for a **21st century argument for rejection based on those 2 principles (*semper reformanda* and *sola scriptura*)** which should not include polemics and outdated Masoretic text / St. Jerome argument as in the answers of the previous question. Another way of stating the question (positively): given 1) fresh discovery in the 20th century into Jesus and the 1st generation apostles's OT background (such as the texts they use) and 2) given Protestants's commitment to the *semper reformanda* and *sola scriptura* principles, **what criteria does it take for Protestants to include *back* the deuterocanonical books that they rejected** 500 years ago in order to fulfill their *ad fontes* ideal of being faithful to the original revelation?