Linux

You can explore a GUI if it's safe to do so. If a user has been burned by easily putting their system into an unrecoverable state, they develop a fear of exploring. "I don't want to change anything; I might break my computer / lose all my work / get a virus!" is a really common fear.

Not to say this is gospel truth or anything. It's just why I virtually always prefer a command line over a GUI. (Within reason.)

• GUIs almost always hides/obfuscates/abstracts things that are going on under the hood in a way that text doesn't.
• Anything I can do from a Bash terminal, I can automate pretty trivially. (Or even just press "up" and then "enter" to quickly redo it a second time.)
• Pointing devices feel awkward and imprecise for a lot of operations. Pretty great for FPSs. Sometimes a necessary evil for image editing. Slow and sucky for setting a boolean value or putting your text cursor between two specific characters in a paragraph of text.
• It's good to be able to use a terminal when your GUI's broken or frozen. Ctrl+alt+f2 or if even that doesn't work, ssh in from another box (or your phone).
• It's a lot easier to paste a Bash one-liner into a chat or text file than describe a series of mouse clicks.
• You learn a lot using Bash that you don't learn using GUIs. And that can come in handy.

“Guessing commands” isn’t the way to go about it. Read the man pages. Read the help for commands. Read a tutorial or some examples.

$ command -h
$ command --help
$ man command

I have a lot of tab completions installed, too, so i can also just hit tab to get a list of all possible options, etc.