Destructive in that many edits are lossy. Change the transform of an object, then go do a bunch of other edits, and then go back and edit that same transform again. What you'll be editing now is the edited image, not the original one (as in Photoshop), so there's massive data loss and it looks absolute crap. If you want to edit with the original image as origin you have to undo all edits back to before you edited the transform the first time.
Non-destructive editing should be coming in the future, and they might have implemented some non-destructive things since I last used it.