I think that in a way we have kept these numbering options out of titles and the main sidebar precisely because of your caveat above—they aren’t about compiling, but having them in the titles in the editor would pretty strongly imply otherwise I think.
The binder, I could definitely see more of a case for the outliner hierarchical numbering option being allowed there. The main reason it does not is the overall design principle we’ve stuck with since from the start: the binder is for the dirt basics, all the frills should be done in the outliner. It’s a bit arbitrary, but it is a thing. 
If you haven’t come across the notion yet, something I do a fair bit of is hiding the binder entirely and using the outliner instead. It does mean one less split, but with Copyholders these days, that isn’t as much of a setback as it used to be.
- This screenshot shows an example from a workflow description, where Scrivener is in fact nothing but an Outliner, the narrow dark brown column on the left, and everything else is a coding editor.
- Here is a practical demonstration of the idea in practice.
- Lastly, if you’re thinking high level navigation would be crippled without the binder, here are some tips on editor navigation, which can make your daily usage of Scrivener more efficient even with the binder still open. (You can probably skip past all of the “Scrivener is an outliner!” stuff, as it sounds like you are very well aware of that.)