The idea was to have a more linear way to express your thoughts and adding calculations. Another big problem for me was that in excel when you want to create various plots for the same multi-variate problem you have to create a ton of copies of your data and formula.

For sharing files, it could be as simple as sharing a text file. You can also imagine a future where you create something and you only share the nice looking html view that is still interactive.

Running locally? not a problem, I already tested packaging this into a OSX app and it was like 4MB and has the same functionalities.