Could someone explain switch statements, to me? Why arent they taught in treehouse?

They aren't quite obsolete, but you do see them fairly rarely. They are very similar to if ... else if ... else but they can be somewhat less verbose and/or easier to read in some circumstances.

Here's an actual example:

function FolderStore() {

  this.folders = [];

  dispatcher.register(function(payload) {
    switch (payload.type) {

      case 'GET_FOLDERS':
        this.getFolders();
        break;

      case 'ADD_FOLDER':
        this.addFolder(payload.content.name);
        break;

      default:
        break;

    }
  }.bind(this));
}

In this example, it's very easy to see that the only thing that matters for the various cases is the value of payload.type. If you were using an if ... else ... each expression would be (payload.type === 'something'). There's nothing wrong with this, of course, but the switch statement puts the important bit right at the top and makes it clear it's the only thing that matters.

The only thing that makes it different from if ... else ... is that tricksy little break, which you can't ever forget. It's probably possible to do really clever things by leaving it out, but I wouldn't recommend it.