In my experience there is a set of things that "traditional" Jupyter notebooks does really well. Anytime you have a linear flow of steps the notebook metaphor works really well.
However, if you are doing things approaching traditional development, where you have multiple sources of data, or loops that require debugging, or basically anything that isn't linear in nature it doesn't work so well.
I wouldn't want to lose traditional notebooks, but I'd love to be able to offer people something like this that offers better debugging and some development tool support, rather than jumping to a full desktop IDE.