"Listening to an audiobook isn't even close to the same experience as reading a book. "

Studies suggest basically the same regions of the brain are activated during conventional reading and listening to an audiobook. Retention of information is also pretty comparable.

"I don't say this in judgment of those who listen to audiobooks. "

No, you just say it in ignorance and condescension which is so much better.

"I'm glad you've found something you enjoy."

I'm glad you feel the pompous need to try to squelch that joy in others.

"When people are talking about how great or terrible the audiobook is, I often find that it has no relation at all to the experience of reading the book. "

Maybe it has no relation to you, but for other people it might. I find I become more aware of the rhythm and sound and general lyricism of stories when listening to an audiobook compared to conventional reading. Alliteration, consonance, assonance, etc. all are more noticeable to me when I listen to an audiobook than when I read a conventional book. The first stories were meant to be listened to, not read. So audiobooks put us back in touch with the ancient roots of storytelling.

"Many times, they even admit that the narration is a large reason for their enjoyment."

It's part of the enjoyment but not the only enjoyment. Plot, characterization, setting, theme, prose, etc. are all also factors in people's enjoyment. A narrator might enhance a person's enjoyment of a story the same as seeing Othello performed might increase someone's enjoyment of reading the script. Narrators can sometimes add an extra flair or flavor to the book or help people hear the story told in an authentic accent. Sometimes too an audiobook allows readers to experience the story as read by the author. That is pretty cool for a lot of people.

"Listeners of audiobooks also probably get a little annoyed when people are talking about books that don't have an audiobook version. "

Many people who listen to audiobooks also read print and/or ebooks. Some people like myself even have Kindle or print versions of books as well as owning the audiobook. Even those who listen to audiobooks exclusively will just find something else to listen to.

"Or worse, a great book everyone who reads is fawning over, only to find that the audiobook has a terrible narrator."

That's why I listen to samples on Audible and only get audiobooks with good narrators. Books with narrators that don't appeal to me, I will just read in another format (print, ebook, etc).

It's easy to take advantage of all the different reading formats available to me in the twenty-first century.