Pascal Becker, this is about someone reviewing portfolios and the presentation of app screens on Dribbble and Behance, not actual users using the actual UI inside an app. There’s a trend for designers to place screens in a 3D rendering of an abstracted, simplified phone tilted at some sexy angle with screen glare over some perfect background, etc. These tricks make things look cool, but they make it harder to assess the actual UX of the screens shown. Therefore it’s “hiding” behind the presentation tricks vs simply showing the actual interface to make it easier to consider. Make sense?