But the limited range and low bandwidth makes it ineffective at a large scale.

It is good enough to usually work at a city wide level and between people within walkie talkie range. It's only ever meant for resilient local comms, it is not meant to be a state or even county wide system even with mqtt

Meshcore seems to be overtaking Meshtastic in adoption recently, and it handles long-haul router placement and high traffic, high density nodes a good bit better for metro areas.