Okay, did we ever see extraction in the show? No. Is it implied possible? Yes. Because we've seen metal benders manipulate metal in many ways. Have we ever seen anybody from an actual canon source shadowbend? No. If people say "well we're out of things we've seen them do, let's go to the most random ideas ever" then we need to start making moves that are heavily implied.
And even then, the goal of the plugin is to emulate the show. Once we have a lot of canon abilities, isn't that when we intend to stop? Since ProjectKorra started and we've had the ability to suggest, people want more and more and complain. Remember back in the days of Orion's plugin? 9 moves for each and everybody still played it for hours on end? Not once whining and complaining for shadowbending, or soundbending, or a super OP move.
The devs work really hard to give us this, and we thank them by saying "Okay, here's what I want now!". Some people make reasonable suggestions like fixing logical errors, or adding more config options. What was the last suggestion that was actually added out of curiosity?
Edit: I found out. The last ability suggested that got added was the AirStream combo. And the most recent suggestion of all was the bending display command change. Some other things are labeled "complete" because they were added before the post was made, or could be achieved by altering your config, such is the case of glass bending.