They're not anonymous, they're pseudoanonymous, which also means carrying a reputation; and if anyone tries to deceive, the community is not entirely full of idiots, unlike what a lot of others in this subthread seem to imply --- all it takes is for someone to find out and provide proof, and the news will spread widely.

The fact that people seem to be scared of and are basically unwilling to make their own decisions of trust in deference to central authorities says a lot about the state of society today... "distributed trust" and communual free sharing was the norm, until companies started to herd users into their walled gardens and control them by using the "security" argument.