CLIs are opaque by definition. With a GUI you can click around menus until you find what you're looking for; with a CLI you can't even begin unless you already know what you're doing. Man pages are no help to newbies; they're either uselessly terse, impenetrably jargon-packed, or both.
It's probably possible to make a CLI that's relatively easy-to-use and newbie-friendly, but I've never seen anyone attempt it. People used MS-DOS for years because it was the only way to access the large majority of software, and abandoned it as soon as there was a viable alternative (Win9x).