One aspect is that brands like can "rotate" their product and sell new stuff to a new generation, but social tech is stuck because (if it's good) it keeps the e

One aspect is that brands like can "rotate" their product and sell new stuff to a new generation, but social tech is stuck because (if it's good) it keeps the existing users, which inherently makes it uncool for new users. The social tech that your parents use can't be cool, by definition, no matter how good it is, the fact that your parents (and grandparents!) generation is already there is a big drawback to coolness. But social tech companies are reluctant (for obvious practical reasons) to periodically create new generations of social networks to capture a new generation of users by intentionally providing them "not your parents' social network".