Exactly. Why would you want a single app that has other apps? You could easily go download a standalone app from the app store that delivers a superior experience. There would need to be some competitive advantage or economy of scale of the single app. But what that advantage is remains to be seen.

Just as an example: both Facebook and Snapchat (and I'm sure others) have tried adding games to their platform. Both efforts have failed because you can get a better gaming experience by playing a standalone game. If you want to play with a friend, you can message them and say "hey, let's play X." There is limited upside to playing in Facebook or Snapchat, and a lot of downsides (limited catalog, performance restrictions, etc.)

One exception to this is any feature that requires exposure to an audience. Social media is very good at exposing people to content. Something like Facebook marketplace can be successful because sellers want their listings to be seen by people and buyers want to go to places that have the most sellers.