Reminder to readers of this thread, that this is about inadequacies in the Help system and whether the Forum can or should make up for them.
Please start another topic concerning “SketchUp uniqueness and comparison to other modeling products” in the main SketchUp category and do not yank this thread off topic.
Colin, note that there are Help feature / page requests still posted in the “Help Center - Report a Problem” subcategory that have not yet been implemented.
A recent example of not being able to find help. Several days ago, I was attempting to help with a question in the forum, and I tired to find the User Guide page(s) describing how to create a local collection (materials or components) and I could not. I feel I have seen it in the past, but cannot find it now.
The OP has a good point about expecting a list of links (index) for each one of the native tools. Looking at the User Guide’s navigation (chapter) list, it is not apparent or obvious which chapter to look in for help on the MoveTool as an example.
All of the terms that a user sees in the SketchUp interface need to appear in an index list (for each GUI language,) so users can look them up in the help. The user will be using the application and come across some control or setting or checkbox, etc. and they’ll need to know what it is for. So, they need to be able to look it up and get a link into the proper help page.
In addtion, MS Windows has the feature of a help button in dialog windows that can be used by users to hover over dialog controls and get some popup help. But SketchUp has never leveraged this ability.
Another peeve. I dislike how sectional (inter-page) links do not appear in the right side navigation list when the chapters are expanded. (Again, as a partial example, see my sectional outline for DC Help that shows the sectional links.)