Welcome to the forum Spartanswimr.

I don't believe that analogy came directly from Tolkien. In the Forward to the LOTR, Tolkien wrote. Later on in this Forward, he mentioned that his experience in the two wars and the situation of England when he was finishing his tale had no influence on the story. And as far as any pre vs. post industrial Britain analogy goes, I believe he meant it only had a very slender basis experience-wise, because the country of his youth was already being shabbily destroyed.

I suggest that you read the forward yourself, and develop your own answer, as I may have it wrong. Others here, may have read some of his letters and can certainly provide you with a more knowledgeable answer.

There always will be this misconception. I suppose the reason is how can somebody create a land and creatures, weave it into a book and was voted best novel and postAuthorID of the century.

Most writers that writes real well normally base their writings on their experience. If the book was an analogy of real things - the book will become so dull. Good books are made up of experience and creativity, with the percentage of 30:70.