And why is around in the first place? I can imagine a future where html5/js combo is enough to convert a set of html pages to a nice offline-supported readable format.
Same deal with MP3 vs other formats. PDF is a sort of gold standard in being able to precisely lay out text and know it'll render mostly right on most devices (even if the format/layout is wrong for those devices).
HTML5 and EPUB are getting there but vary so much between different platforms that till now (and EPUB 3 is changing this) the quality of books in those formats has been hideous production wise. Compare the typical EPUB book against the typical PDF book in terms of whitespace, layout, fonts, and how the author and publisher intended it to look.
Same deal with MP3 vs other formats. PDF is a sort of gold standard in being able to precisely lay out text and know it'll render mostly right on most devices (even if the format/layout is wrong for those devices).
HTML5 and EPUB are getting there but vary so much between different platforms that till now (and EPUB 3 is changing this) the quality of books in those formats has been hideous production wise. Compare the typical EPUB book against the typical PDF book in terms of whitespace, layout, fonts, and how the author and publisher intended it to look.