People will install 20 social media apps for 20 different psychological contexts that have subtly different needs and can use a UI distinguisher to key their brain in on which set is active.

People won't install another social media app if there isn't sufficient incoming social credit encouraging them to use it and the need falls into an existing category. Something sufficiently different can gain an “I couldn't have done this with” credit to overcome some stickiness with.

… maybe. Sort of. I think.

(I wonder what this means for e.g. Facebook's acquisitions of Instagram and WhatsApp, if it's true.)