Well said. There are all sorts of reasons some of an author’s works may well not correlate to other works of same author.
I certainly see a radical divergence in the style of J. R. R. Tolkien, even alongside a thematic unity.
I would love to take The Hobbit and The Lord of the Rings and subject them to the methods used. From changing terminology (using the word “goblin” to “orc”), to changing the Runic alphabet, to the overall darker tone, to the higher vocabulary, to the sentence length, to the various lighthearted narrator’s commentaries to the reader in The Hobbit that are entirely absent in LOTR (e.g., “Gandalf came by. Gandalf! If you had heard only a quarter of what I have heard about him, and I have only heard very little of all there is to hear, you would be prepared for any sort of remarkable tale.”)… all these observations are the very sort used by NT scholars to conclusively demonstrate different authorship among Paul’s letters.
E.g., The article you linked notes a common argument about sentence length and vocabulary. Again, for comparison, consider the line in LOTR… “Luminous these were too, beautiful and yet horrible of shape, like the demented forms in an uneasy dream; and they gave forth a faint sickening charnel-smell; an odour of rottenness filled the air.”
You won’t find language nearly so advanced or such complex sentence structure in The Hobbit, nor such high vocabulary (I searched… The Hobbit doesn’t use the words “luminous,” “demented,” “sickening,” “odour,” “rottenness,” or “charnel.”).
These are exactly the kinds of arguments and observations used to prove Paul didn’t write said disputed epistles. Keeps me very skeptical of how effective any such methods could ever be. (And I didn’t even bring The Silmarillion into the discussion. If I trusted the methods of these NT scholars, I would have to conclude that Tolkien’s corpus was composed by no less than 3 authors.)