I am quite impressed with your research and knowledge. The idea and myth comes from the advertising that was true at the time without the disclaimer it referred to inside and outside cabins. At that time balconies were limited to suites. The advertising was so successful people still relate to it.
I am glad you ended your post saying the inside and OV are larger than most ships. I know I am preaching to the choir
Jim C. went on Norwegian last year and posted pics of his cabin..it was way smaller than a CCL same Cat Cabin. I get what your saying about the balcony cabins as a comparison.