Yes i agree with OP and i also do it when i would join some bounty because so many ICO that are scammed many people. But i also see for bounty like social media there are many bounty hunter maybe does not do some investigation the join as many as they can and in the end they don't now if their work does have paid. So we must carefully when join bounty do your own research, choose trusted BM , reading carefully whitepaper and roadmap hope this can help to avoid scam project