I’ve felt the potential of interfaces like this when you dive into a contained environment like Anki and Readwise. These are examples of products that show you things when they “feel” like you should see it. To some degree this removes the burden of choice from your behavior, which is freeing. Of course, currently these are contained interfaces that require user choice to engage with them in the first place.
The OS level system has been thought about by Andy Matuschak as part of a potential Spaced Everything future, as well as by Rene Ritchie in what he calls SiriOS.