People complaining forget what the industry was like before audible. It was terrible. Audiobook cost an absolute fortune, and selections were very limited. Audiobooks in the late 20th century were, I imagine, simular to paper books in 18th century. Something most of the population could not afford to own.
I have been listening, and loving, audiobook for a very long time audible was, and still is, a breath of fresh air.
Combined with the similarly lax attitude to drm as the amazom kindle, removing drm is simple.
Audible has created a market that publishers were either ignoring completely or extreme price gouging (or some of both) .