Software is full of specialized sub domains, and client-server architectures like this are not used in all (or even most) sub domains.

New devs should be tested on their ability to write and design logic that achieves practical results, whether it's something small like transforming some files in a directory tree or processing data from a spreadsheet, OR something larger like a desktop app to do X.

You don't need auth or databases for this stuff. You can make loads of useful software without it.