I'm not sure I agree. For example, I find myself fast-forwarding Coursera videos because the teachers just don't understand where it makes sense to slow the pace or where to pick it up. I find myself skipping huge parts of YouTube videos (my interest is hobby stuff) because the author just doesn't understand I already understood the idea, the take is getting boring (or just not showing the interesting stuff), and they should just cut ahead.
I find producing mediocre audio/video is easy. But quality audio/video is as hard as quality text, if not harder.
I’m not making any statement on the average quality of audiovisual content, just the barrier to entry for the production of that content.
FWIW I do a lot of skipping and fast replaying too. My podcasts are usually around 2.5x. Most people perform-talk way too slow. If I weren’t able to listen that quickly while doing dishes or similar, I’d normally prefer to read.
That being said, one factor you might be discounting is that producing 1 hour of quality audio information takes much less time than producing a quality 1 hour read. There are a lot of people who are great conversationalists, but not great writers.