Yep that was the original idea, from way back, although I'm sure somebody in the 1960s thought of it too.
I've had a tree-based block-editor CMS (as my side project) for well over a decade and when Jupyter came out they copied most of my design, except for the tree part, because trees are just hard. That was good, because now when people ask me what my app "is" or "does" I can just say it's mostly like Jupyter, which is easier than starting from scratch with "Imagine if a paragraph was an actual standalone thing...yadda yadda."
I've had a tree-based block-editor CMS (as my side project) for well over a decade and when Jupyter came out they copied most of my design, except for the tree part, because trees are just hard. That was good, because now when people ask me what my app "is" or "does" I can just say it's mostly like Jupyter, which is easier than starting from scratch with "Imagine if a paragraph was an actual standalone thing...yadda yadda."