As the barriers between artists and their fans have fallen, and as artists have made themselves more accessible in the hopes of building brands that will help them stay employed, we’ve seen a number of unfortunate incidents where fans cross the line between expressing disappointment over art and deciding that the people behind that art need to be punished. The latest battlefield is the Cartoon Network show “Steven Universe,” where a storyboard artist decided to quit Twitter when fans got aggressive over plot developments, launching accusations of homophobia at her (the artist in question is gay).