Kind of sad how ad-hoc mode was such a a failure. I always imagined how cool it would be to have a huge number of devices all connected to the internet through each other but it was hard enough to just get two devices talking.
Hotspot mode destroyed the use of connecting to internet. It is easier for devices to connect to hotspot than setup ad-hoc connection. My impression is that there is assumption that WiFi Direct isn’t routed.
Today we have vastly superior possibilities and yet, apart from some niche efforts like the LoRaWAN, a "free mesh" is still not a thing.