Mesh networks like meshtastic have shown that they can be run on very low power meaning they can continue to route messages with the power from small solar panels. This makes them more useful in disaster or wide scale power outage scenarios than only as an anti-authority measaure.
Who's going to pay to create all the nodes. You need a lot of them in normal times when it is just enthusiasts sending test messages and if large numbers of people start sending real messages you will need more.
In practice it seems that Meshtastic isn't really up to the task, unfortunately:
https://www.reddit.com/r/meshtastic/comments/1inrm25/is_mesh...
https://www.reddit.com/r/meshtastic/comments/1fy95kj/lets_ta...