The fact that very few types of writing actually work well in book format? I've written a novel: It takes a lot of work and a lot of effort to make one, and it'

The fact that very few types of writing actually work well in book format? I've written a novel: It takes a lot of work and a lot of effort to make one, and it's very hard to write one without padding it. Most things novels deal with can be dealt with better in movie/short story/blog format. Just because we as a society don't appreciate how niche books are doesn't mean books aren't niche.