I still consider KYC to be risky or SMS to be unreliable so proof of humanity will never be a real concept because it is really hard to achieve. We live in a digital world and we require digital proofs, when you make it about real life and real humans that becomes something much more riskier and people would probably stay away from it.
There was a currency who wanted to make a proof of humanity with KYC and asked people to provide ID and pictures and so forth just like how the exchanges and casinos are asking for KYC, same data but they would basically airdrop to those people the tokens they were promised. What happened was people would basically get these information of everyone they could get their hands on and still collect all the money themselves and sold those, the token failed miserably. So proof of humanity is a good idea but can't be executed properly.
Or you could simply use an identity scheme that identifies people uniquely without de-anonymizing them or violating their privacy in anyway. With that, no single person ever knows the real identity of ID owners even when they go through kyc process. You could tie the owners decentralized Reputation to their IDs to make the whole network safer.
Unique identification scheme that is fully control, and only known by their owners will save decentralized networks alot of troubles in the future
