Editing on your blackberry was even clunkier than the touch affordances that this post is about - just cursor keys, right? Now, you might argue that if you can type fluently you won’t need to edit as much - but the point here is about enabling mobile devices to be much more than just message input devices, but actually to do things like revise documents. You’re not using text manipulation affordances just to correct typos but to make significant changes to existing bodies of text.