What changed
Helium: the proof was coverage. The customer was someone else.
The paper's mechanism rewards hotspots that can show they hear one another. Hearing is not paid traffic.
Original thesis
A wireless network whose operators prove coverage and are paid by the protocol, instead of by a single carrier building every tower.
What changed
Proof-of-coverage can be satisfied by radios arranged to witness each other. Useful data transfer is a separate fact. The network also moved its ledger over time. Cite the document you mean, not the brand.
What remains useful
Any DePIN design that pays for a measurable stand-in will be farmed at the stand-in. Read the reward function before the map.