I absolutely agree! I came here to write this very request, but I would not have put it as eloquently. I have really struggled to get comfortable with Obsidian, and today I finally realised why. I have a lot of areas of responsibility and projects, and on email I manage to keep it all well organised and it feels controlled. And it is exactly because folders and the emails inside them are two separate things. Navigate the folders on the left, see the the emails on the right.
For whatever reason when folders and files (notes) are mixed I find it that much more difficult to navigate and visualise. And I think part of it is they are not the same thing, at least maybe for people who think a certain way. Mixing them makes it feel all disorganised and obscures the boundaries. I really believe this would provide a huge quality of life improvement if it were an option (for some people at least).