Screen with 20 checkboxes is never going to make simple GUI. I can imagine “configuring most common cases should be possible with simple GUIs” but *everything* is going to be challenging.
The situation isn't identical, but broadly speaking the goal of having a GUI for everything which is still good and powerful feels to me like it should be possible, albeit not easy!
There are people that believe that everything should or can be easy.
It is just painful to watch those people.
Yes you can build some software that will make FFT useful and you don’t even know you use FFT in an application.
But telling if an image is important for you to not compress it lossless way or 1000 of your images is or is not - well you have to sit down and make decisions and go one by one or make some rules that won’t be perfect.
The latter implies only common needs covered in the GUI.
Edit: the complete source paragraph does go on to list services. Which confirms they’re talking about every service rather than every imaginable operation.
Most likely if you are an expert you already have one liner ready to configure "Expert" stuff and you don't want to click checkboxes.
Like yourself, I find the CLI more intuitive than a GUI (so much so, I even wrote my own $SHELL and terminal emulator), but it's difficult to argue for or against their specific approach when the subject is based on speculation.
If you're able to share a screenshot of their "Expert" tab to show how it's not particularly easy to use, then that would go a lot further to demonstrate your point.