On the desktop, most Mac apps looked like most other Mac apps. On the web, authors often created their own components, and could completely customize their look. Mobile has largely tacked towards the web, where Airbnb looks more like Airbnb than it does like any other Android or iOS app.
Spotify uses its own skin, as does Windows iTunes. NetBeans uses Swing with the Nimbus look-and-feel. Firefox and Chrome use their own toolkits (e.g. on their Settings windows). Even Microsoft Word feels like 'its own thing'. UWP applications don't tend to feel native. At least RoboMongo and the CMake GUI feel like proper Windows applications, but they both use Qt.