South Korea's booming 'webtoons'
One factor not discussed in the article is the differing attitude towards exports, piracy and copy protection.  Historically, and even today, it's extremely difficult to legally view lots of Japanese content outside Japan, yet Japanese producers pursue copyright claims with rabid fervor.  Japanese publishers for books and music were also extremely resistant to move to e-books, digital downloads or streaming.For whatever reason, South Korean publishers were not as myopic, meaning their content could be more easily accessed -- at first technically illegally, but soon there was a groundswell of demand that led to large-scale legal rebroadcasting (TV stations showing Korean dramas etc) and that then led to today's juggernaut.  Manga is just the latest example of Japan losing a market that really should have been theirs for the taking.