Yet writers never seem to give this sort of treatment. Popular novelists tend to be less wealthy/successful than their musical or audio creating counterparts, bloggers find it harder to get attention online than YouTubers or podcasters, and generally it's easier to promote other forms of content online in general, with many places being far happier to let people post their videos or artwork than articles or short stories.
So why is this? Why is writing in general seemingly so undervalued now, especially online?
While professional writers may be quite skilled, the gap between what they do and what the median adult does seems traversal. The psychic distance is much larger for other creative endeavors.
I don't think it is at all related to what others said about "most people can write" (those people have probably not tried actually writing fiction) -- especially not with today's music production tools and how easy they are (FLStudio, Garage Band, etc.).
You also have to keep in mind the power laws are just slightly different here. There are some very very rich writers, that are far richer than even the best-selling musicians of all time. Stephen King and J. K. Rowling, for examples.
It's just a market. More people are interested in consuming and paying for an album, because it takes 45 minutes to listen to, whereas a single book might take 10+ hours to read.