No, lookup e.g. the JavaScript console in every web browser to see what I mean. You can place the cursor anywhere on a line while editing a command. Regular keyboard commands which work in the rest of the GUI works such as holding shift and move arrows to mark text.

Completions pop up in graphical popup boxes. A command line interface doesn't need to emulate a 1970s teletype electro-mechanical device. They can use modern features that exist today.

Plan9 is a good example of what you can achieve if you design this from scratch. You should check that out at some point. They have a lot of interesting idea and it is a system made by the same guys who made Unix so it is really an imagination of what Unix people would do if they could utilize modern technology.