I asked for this feature in 2017 when I was recording audiobooks and needed notes about chapters, characters, etc. Now I’m just recording blogs, so each project is a simpler one-off.
I think there is a strong case to be made for proximity: the ability to pop up (or have a panel, a la Cakewalk example above) an editor. Simpler than Alt-Tab to an external editor.
My other argument is for a single file. Audacity made life simpler when it moved to sqlite and abandoned the XXX_data folder + XXX.aup file structure as I regularly move projects between machines. A separate text file would reintroduce this complexity.