I want to see some (or a lot of?) chat history offline, and then send msgs while offline. I don't want it to scan the network, delay loads, or blow up in any way just because the network is down. Think about the Whatsapp or Telegram experience, as opposed to Slack or Facebook Messenger. If you are in and out of the subway, or in elevators, or just where there are spotty networks, the mobile experience blows for anything but the super popular and consumery chat services.