The result is the same. Every sub-notebook is a notebook that can contain more sub-notebooks, but there is no such thing as a mere folder that can be placed ins

The result is the same. Every sub-notebook is a notebook that can contain more sub-notebooks, but there is no such thing as a mere folder that can be placed inside another folder without also creating a confusing space where notes can hide inside the notebook but not alongside its sub-notebooks. The other way to interpret it is just a very poorly planned UI that uses separate panes to list folders and notes that are located in the same hierarchy position. Either way, it’s madness.