This is true in politics and religion as well, the outward facing representation of a group is often defined by its loudest proponents. They are often not representative of the group. But external perception is still important and easily shaped by loud / repeat voices.

Disavowing certain behaviours works on a personal level, but otherwise people who wield power in such groups have to try and use that power to try to improve external perception often in spite of the many vocal members of the group.

The world is full of self-selected spokespeople.