A GUI editor can do everything a terminal based emulator can; there are lots of things a GUI editor can do that a text editor can't. Some examples were given in another reply. Others include inline previews of things like latex equations or images, documentation tooltips, unobtrusive autocomplete popups, proportional fonts, proper mouse interaction, working well with window managers, and basically complete freedom to design the interface in a way which is optimal for whatever task rather than shoe-horning it into a grid of text.
What is the advantage of terminal based editors? As far as I can see, ubiquity, which is made less compelling when you need a host of plugins to do the things you mention.
Terminal editor enthusiasts seem to be under the effects of something like the Blub paradox, where any feature of a GUI editor described to them is dismissed with "why would I ever need that?" while anything in terminal emulator can do is considered essential.
What is the advantage of terminal based editors? As far as I can see, ubiquity, which is made less compelling when you need a host of plugins to do the things you mention.
Terminal editor enthusiasts seem to be under the effects of something like the Blub paradox, where any feature of a GUI editor described to them is dismissed with "why would I ever need that?" while anything in terminal emulator can do is considered essential.