1. To know what the terminal is. Most people do not.
2. Either Homebrew or MacPorts installed. At this point you've lost the majority of the people who vaguely know what the terminal is.
3. Familiarity with how unix commands work, what "flags" are, how to write them, how to specify filepaths.
4. How to debug those commands when you invariably get it wrong.
5. Since fd just dumps filepaths, you need to know how to inspect them further and open them.
Yes, $6 is more than worth it for many people. All you need are eyes and the ability to use a mouse and keyboard.