People have a mental cap on what text should cost. If someone creates instructional content that provides thousands of dollars in value, they can sell videos for $200+, but a book version is hard to sell over $50, even if both provide the same value. Even for free content it is easier to monetize YouTube than it is to monetize a blog.
If we want people to create more text-based material, it needs to have similar financial incentives.
I think part of this is how society consumes information.
In the 80s, you mostly had books. Sure, there were some video courses, but a majority of the learning was through books.
Now, people consume most of their information in video formats. Think about the rise of Vine, Youtube, TikTok, and the 100s of others out there just like them.
They are growing like weeds, because that's apparently how the public now likes to consume media, info, etc.
I assume most of this video bias comes from the ease of monetization (for content creators) on Youtube. That might in turn come from some mental cap held by viewers on the value of text vs. video, but I suspect it has more to do with the number and value of ads that can be shown by the platform. Some random blog platform is going to maybe have inline image ads, while Youtube has unskippable video ads which I assume are valued more by advertisers.
I have no data to back this up but just taking a stab in the dark - a possible reason might be because people generally tend to prefer learning from someone talking about the subject matter?
I know most all of us here are techies and very used to cracking open books and documentation and text tutorials to teach ourselves stuff, but many people are not like that and especially if you're new to a subject, sometimes books just don't help things to click as well for some reason.
There's probably something to do with the way material is structured and presented differently between talking about it and writing about it, but I wouldn't know what to say about it.
I dunno, just a guess because it's an interesting observation to think about.
If we want people to create more text-based material, it needs to have similar financial incentives.