With that said, requiring different rules for children seriously increases barriers to entry for new services hoping to attract users in areas where these rules take effect, and kids will ALWAYS find ways around it. Nudges like snap streaks and the Like button encourage daily active use, but they also encourage actual social interaction between people to some degree.
Additionally, nudges like the Like button or Snapstreaks, though they do encourage a potentially unhealthy relationship with technology, also encourage social interaction with peers. It's certainly more complicated than "these are bad!"