[tfehring]

None of the features of CLIs that you described qualify as discoverability IMO. Tab completion, etc. only work if you know the name of the command that you need, and few to no CLI utilities or commands are named well.

Say you need to remove duplicates from a list, for example. If you happen to know that the utility to do that is called `uniq` then it's useful that you can use `man uniq` to see the available options, but if you don't already know the name of the utility you're looking for, you're stuck Googling for it. (The name `uniq` isn't obvious but at least it's intuitive. For the many commands that are neither obvious nor intuitive, good luck.)

Compare that to, say, Excel, where if you press Alt,A to bring up the Data tab there's a nice, big button labeled Remove Duplicates, with an M on it to indicate that the full keystroke sequence for that command is Alt,A,M (fewer keystrokes than ` | uniq` even with tab completion, for what that's worth). So in addition to accessibility, there's also discoverability.