How the “Ex. Tele Conv.” function on the GX8 can be useful

There is a function called “Ex. Tele Conv.” on the Panasonic Lumix GX8 camera (and probably on most of the other Lumix cameras) that makes it possible to crop an image in camera. I saw it described as “useless” in a discussion on a Flickr group some months ago which seemed at bit harsh to me. Of course, for RAW...