I can’t confirm this, there are apps that are well described.
But in the end the documentation depends on the developers. And most developers (with a few exceptions) program the apps free of charge in their spare time. If you have questions about a specific app, the first thing I would do is to check if there is a post especially for that app. If not, you can always ask the community or try to find and contact the app developer.
In the current case, it’s more a general problem, as it doesn’t refer to a specific app. And I agree with you that the documentation from Athom is bad. Unfortunately, I can’t give you a more positive answer.
However, I can tell you from experience that Fibaro is no better.