Linux

Package management is probably the biggest thing a Linux user might need to use the terminal for. The graphical package managers used by default on most desktop environments are far too limited.

KDE's Discover for instance is capable of installing (graphical) desktop applications, uninstalling packages and performing updates. Sure, it supports native packages on the majority of distros through PackageKit, as well as Flatpaks and Snaps, but it can only perform very basic package manager operations. I imagine most users will at some point need to install a package that isn't a graphical desktop application, such as a driver or an optional dependency and they will need to use the terminal for it.

To my knowledge, this is also the state of most other graphical package managers that take the form of "software centers" like Discover. More powerful graphical package managers do exist, usually specific to a specific package manager such as Octopi for Pacman. Few distros ship with them, however. I believe one notable exception is OpenSUSE with YaST. There's also dnfdragora on Fedora, which is pretty basic, but might be good enough for most purposes.

I think tools like YaST help to save time, instead of editing the bootloader in config files, you can simply enter, search for "Boot Loader" and edit there, be following a tutorial or official documentation. I sometimes prefer to use YaST just so I don't do things wrong. it's like the old Control Panel in Windows.

To all the people pointing the many inconsistencies of Linux/specific distros, I recommend The Unix Haters' Handbook

My aunt is using Linux without terminal since 2016. Though she at least knows how to open terminal and paste commands when it's necessary (needed a couple of times).

You can use Linux without a terminal, but life is so much easier to just remember few letters (command) and pressing enter instead remembering 200 places where a setting is. You can also always just do sudo pacman --help.