A core issue:
People don't want to be overwhelmed by undifferentiated material.
Like the web at large, many content-specific sites (e.g., for independent music) enable
virtually anyone to present their content.-- The material tends to be of wildly uneven quality. -- A lot of it won't interest much of anybody other than its creators. Most people like their content culled or filtered in some way. -- They prefer subsets of just what's most interesting. -- They like being able to choose from multiple subsets... ...for the same reasons they like having a choice of clothing stores. Purveyors of Web content can learn valuable lessons from brick-and-mortar retailing.