What's the big deal about backing SoS Notebook with a workflow engine?

After I announced the release of SoS Notebook as a third-party multi-language kernel for Jupyter, I was asked repeatedly (e.g. On HackerNews, AzureNotebooks, and in reviews to our manuscript) the following question: Why did not you use an existing multi-language notebooks (e.g. Apache Zeppelin and BeakerX) or contribute a multi-language feature to the core of Jupyter or JupyterLab? There were several technical (e.g. architecture of the current Jupyter core not suitable for multi-language support) and practical (e. Read more