Justin Searls, a big name in the web dev community, has this great quote:
Software development is just putting spreadsheets on the internet.
I totally agree! My experience working at a handful of companies over the last 4 years has been that the most common asks, the most common stories, are forms and tables.
A form to create or update something. And a table to display an index of those items.
In that vein, one of the most effective, relevant, impactful skills we could have our contributors working on in order to prepare them for real world software development is precisely this: creating forms and tables.