What do you mean? Jupyter notebooks are usually pure Python apart from (sometimes) interactive widgets, which have Javascript behind them since it's in a browser. I don't think this is much use without widgets, so maybe you mean something else?

I mean why can't I write python outside of jupyter and generate these dashboards? Or can I?

You can if you use Panel (panel.pyviz.org); it does not depend on Jupyter in any way (but like Voila, works well in Jupyter).

If you want to avoid Jupyter Notebooks you can look into Dash or Bokeh Server.

Jupyter is convenient though :)