When the iPhone first allowed apps in an app store I had a conversation with another developer. We brainstormed an idea of an application that would allow you to aggregate all of your conversations with a person. Instead of opening the phone app, the messages app, facebook, twitter, etc. you would instead open the "Joe Smith" app and all of your conversations with that person across any medium would be aggregated in a single place. It is a bit like SoA vs. AoS (Structures of Arrays vs. Array of Structures). By transposing the relationship between app/person to be person/app it could change how we view social media.
What I've found over the following 12 years is that application producers are extremely hostile to anything that would take the user out of their application. It reminds me of early 2000 era websites where external links on some sites were not allowed.
The reason why RSS and similar aggregators do not work has nothing to do with technology. Any technology that allows you to follow the stars of a social media platform outside of that platform (or aggregate across platforms) will face a level of of opposition that is likely to be insurmountable.