The use cases stem from groups needing coordination in roughly the same area, with no internet. Disaster recovery efforts fit this exactly:

Doctors Without Borders feeding centers in a famine far from anywhere, searching for people in the rubble of a building following an earthquake, searching for people in a refugee camp, etc.

Verizon went down in the US this past week - perfect use case for Bitchat (or Meshtastic with a repeater or some other LoRa BT network). Verizon goes down while you're at the mall or store or Disneyland or whatever and you can still text to find each other.

300m max range with line of sight would cover something like when I go to visit my parents who live in a desert canyon with lousy mobile phone coverage, I can send a message that I'm at the gate and put the dogs in the garage.