They were banned for performing obscene acts in public. One is obscenity masquerading as art, which we took action against. Performance art is a separate matter. Performance art relies on strong psychological interaction between the performers and the audience. It makes for a more intense experience and it's a device which is as old as society.
All religions use it.
If you attend a charismatic revival, they require you to do things that make the experience a more psychologically involved one. The Communists use it in cells, where they encourage young recruits to narrate their experiences and make certain commitments. Group therapies employ the same techniques, like Alcoholics Anonymous. So there's nothing new about performance art. But we are mindful that if misused, it can be exploitative and manipulative.