Being a techno-optimist doesn’t mean that we should be in favor of every possible use of technology. Instead, it means believing that humanity can learn to use new technologies for its ultimate benefit. Putting guardrails on where and when a technology can be used is a standard method by which human society figures out how to use that technology — we don’t drive cars on lawns, or do karaoke in the middle of business meetings. Putting away smartphones during class seems like yet another thing that we’ll look back on as obvious half a century from now.