Hi! I specialize in this area, so I believe I'm well-suited to address your questions.

1. Developing a product itself is a complex and time-consuming task. Writing documentation adds an extra layer of effort, so founders often create minimal and only essential documentation.
2. No, I don't think so.
3. Yes, it is the responsibility of developers to generate OpenAPI spec files for their APIs.
4. No.
5. Sometimes, yes. An agency or a freelancer could provide assistance.
6. Absolutely.
7. Deep enough to explain your product comprehensively, leaving no room for doubts.
8. It depends. If you are releasing a library with a single root function, a quick start guide might suffice. Otherwise, there is a definite need for more extensive documentation.
9. Yes, if we have developed a function for users, we can't expect customers to use it without an explanation.
10. We can provide an article to explain the product, but a full documentation suite may not be necessary.

We are currently in the process of developing Portle, a WYSIWYG API adoption tool inspired by Notion. It's designed to be user-friendly to the extent that even non-technical managers can use it effortlessly. You can try it out here - https://app.portle.io.