I used a BBEdit notebook file last week for creating copy for a pamphlet formatted with Affinity Publisher. It was a very nice experience.
I used soft wrap with two returns to separate paragraphs. Before copy-and-paste into Affinity text frames I used the Text->Remove Blank Lines command. That let me edit with nice, natural paragraph breaks while letting Affinity see one CR per paragraph break.
Restoring the file to edit mode is done with either a command-Z (undo) or search-and-replace for one newline, replacing with two.
I think this is the first time I've used a notebook for anything other than a quick experiment to see what it does.
Likely, this is how I will create Affinity Publisher documents in the future. AP is cool, but it's a pain to compose in. Which is ok, that's not what it's for.