I am working on a modernized feedly alternative and thought about this. But my real Problem for this feature would be to automate face/feature detection. Thumbor claims to be able to do this. But I am not convinced that this would work good enough at scale and also be fast enough. And even Flipboard has cut of faces, so maybe nobody cares?
object-fit doesn't solve the problem, it is similar to using background-image and set the background-size:cover. Still when the container's width/height ratio doesn't match the image's, there is risk that image could be inappropriately cut off
Cool. There was a noticeable delay on FF from page load, to when the images resized.