Also true, but I don't think we need to enforce that kind of standard for personal hobby projects. You're not under any obligation to convince people that your project is worth being interested in, unless you specifically want other people to start using it.
You are right, it's not something that needs to be enforced or demanded on a personal hobby project.
You can write documentation and software for yourself, and share it for no particular reason, or write documentation/software for other people, and share it to help others. If it's the latter, you might care that other people read the documentation, because you think it will be useful and helpful and you want to help them.
As a non-expert, I like having the main and most relevant use cases and underlying motivations of authors and users made obvious. For me, having specific use cases in mind makes documentation easier to read and interpret. If I were an expert in a field and felt the motivation for the documentation was obvious and self-explanatory, I might not feel the need to have it explicitly articulated.
When I write documentation, I often need to refer to the Motivation to stay motivated and stay on target. What are all the great outcomes that are going to come about as a result of the documentation existing? If I didn't have those in mind from the outset, I might not want to write the docs.
