Originally Posted by Hamlet53
Makes sense. I think the real question is why some of the real 'heavy hitters' in terms of book uploads continue to upload IMP, LRF, PRC, but not EPUB? Especially since LRF was really only ever a Sony specific format and Sony has now abandoned it in favor of EPUB in their store.
A lot of people use Book Designer to create the books and it does not support ePUB. All of the Sony devices can still read LRF and many think this format produces a better looking book that some of the other formats.