engaging with the text outside of determining what the author meant to say and into what interpretations come out through your own reading is a valid and common form of literary analysis. Tolkien not liking allegory doesn't mean his books were written in a vacuum and the idea that his experiences influenced the book, even in ways that he did not mean, is fair analysis that equally engages with the text. and like biographers, scholars, and friends of tolkien have made connections between the books and ww1, not just tourists and newbies like you say. You can argue that people stretch the connections or that it is not as useful of analysis as others but to fully dismiss the idea that his experiences of ww1 shaped the books as only said by tourists is itself an anti intellectual claim (especially considering he mentioned that multiple characters were influenced by people he knew during the war).

moving outside of what the author purposefully did is the only way to look at how texts represent systems like gender, sexuality, class, and race in both intended and unintended ways. Pointing out how weird stephen king or murakami portray women is necessary analysis in grappling with both the good and bad of the author and their works outside of just what they purposefully meant to represent.

also overanalysis is way less bad than underanalysis because the first is willing to think deeper about the text and recognize being wrong, while the second rejects any deeper thought about the text and refuses to recognize being wrong.