More thematic exploration vs. allegory. Tolkien despised direct allegory. He thought Lewis went too far with allegory in his works.That didn't stop his works from featuring a healthy quantity of allegory.
He was very conscious of influences on him and his works but he would avoid allegory on purpose.
Even if they did, that wouldn't be allegory.
The leaps in logic in nearly every paragraph beggared belief. I tried to find the thing again, but I couldn't (thankfully). I believe it was a comic book-focused site, and the writer was the site's webmaster.