When you see someone who doesn't know how to open a terminal, and log into a server at the command, you can assume they also don't know much about networking, DNS, firewalls, shell scripting commands, or how to configure the services upon which the application's stack runs, like web servers, application servers, caching services, or even databases. You're right; it's trivial to teach that one thing, but that particular one thing implies a learning gap about a lot of other things.