It's actually as simple as this. New authors, building their customer base, need physical bookshops. Physical bookshops are lovely tactile, friendly, expert, welcoming places. Physical books, which can only be seen and handled in physical bookshops, are lovely, tactile things. Destroy those bookshops, and the very commercial and cultural base to the book industry is destroyed. Once and for all. Like Humpty Dumpty, it can never be put together again.