From a brief look, I think he's trying to position it for "Exploratory DOM Analysis". The intro demo looks scheme/smalltalk like in that you are creating the structure and primitives as you go (as demonstrated by changing 'ivory' to 'red' and watching the syntax highlighting change in realtime).
I understand how we got here, but it's a shame that javascript frameworks and libraries aren't easier to just play with in the browser. It's just JS, you should be able to play with it quickly in a lightweight environment. This approach excels at that. This approach brings back the whimisical possibilities of HTML/JS. I'd love to see more stuff like that and less TS, rollup, webpack,...
edit:Actually after reading a bit, this is being proposed for data analysis. I think that's a poor fit for this approach