It doesn't prove that LOTR wasn't a popular series before the movies, lol. It just proves an already popular series got even more popular
Just like if you link at an article about Top Gun: Maverick's success at the box office and say this movie has made Tom Cruise a popular star and claim he wasn't popular before it. The movie did great at the box office, but he was already a popular star WELL before this movie. This movie just ADDS to his popularity.