Is it a good practice to use a single fragment to display the UI instead of the activity?

As the title states, does it considered as a good practice to use a single fragment within an activity to display the content? I began to notice that more and more developers start to use the fragment as an insulation layer to separate the lifecycle logic from UI that activity (sorry, fragment) displays. The most recent example that I stumble on is the architecture blueprints provided by Google developers. They use just one single fragment for UI and while the activity handles ViewModel and all the navigation between screens.

So, is this a good practice or just a personal preference? Would you care to share your opinion on the subject?