I don't have to. There were plenty of signals on how shady the HEX project is from the days it was launched. Although it's not proven to be scam or not, I know (for myself) it's just a scheme.
My point was that the signature wearers may actually not get paid at all. And @SiNeReiNZzz point is also very good: they may actually get tagged too.
Especially in the altcoins area people still join bounties head first.