When I worked at Amazon Cory Doctorow came to my office (we shared it with Audible) to give a talk about his book, and host a Q&A. He said that he publishes his audiobooks as albums on Amazon Music because that supported DRM-free playback when Audible didn’t.
He signed my Kindle with the phrase “If you can’t open it, you don’t own it” and drew a skull and crossbones.
Hard to argue with him. Glad I don’t work for Amazon any more.