Online-initiated grooming presumably begins outside of e2e'd 1-on-1 communications. Seems social media platforms have a bunch of options to help prevent that, and keeping e2e. (CSAM is a different sort of crime and must have a different solution). Facebook knows the age of its users, right? There's no good reason a regular strange adult's account should be privately communicating with a teenager (aside from special services like a suicide or domestic violence hotline).
Twitter/Reddit? Kids shouldn't be on those. They're full of porn.
Twitter/Reddit? Kids shouldn't be on those. They're full of porn.