I think there is a place for both chronological and personalized feeds. Chronological works well if the realtime component is absolutely essential to your app.

I think there is a place for both chronological and personalized feeds. Chronological works well if the realtime component is absolutely essential to your app. For apps that have a lot of content or users visiting infrequently you will often want to show the best content, not the latest content. That's where the personalized feeds come in. I believe Twitter and Instagram are doing this because the chronological feeds don't work well for a large portion of their users. You do wonder why they don't disable it for their most active users. (why try to reorder something if the user sees it all anyway?) We provide both chronological, ranked and personalized feeds over at getstream.io Demand for personalized feeds is definitely picking up rapidly, also among smaller apps.