How did they end up thinking that everything must be done with terminal while using Ubuntu?
Most guides on installing things or help on fixing things will offer terminal commands, so I can see how that could certainly lead to that feeling as a new user.
Also depending on the DE and stuff certain very basic obvious settings are not available in the GUI, like fractional scaling on KDE which has to be done by editing some config file first.
My samsung S21 has the option to restrict an app and prevent it from ever running in the background, maybe that would do it if your phone has a similar option?