There's no need to say something rude like that. Just because an artist has their comments enabled doesn't mean that they think that their artwork is "flawless" and that people won't send them negative comments. Every artist has thought that their art sucked at some point which helped them improve to get to where they are now. They also know very well that people will send them negative comments because it happens to everyone. Having comments enabled is a way to get advice, to get to know other people, to get to know what people think about the art that they make. Sure, some people may think what you said, but there's a very low population that does.