Gernsback's initial editorial approach was to blend instruction with entertainment; he believed science fiction could educate readers. His audience rapidly showed a preference for implausible adventures, and the movement away from Gernsback's idealism accelerated when the magazine changed hands in 1929. Despite this, Gernsback had an enormous impact on the field: the creation of a specialist magazine for science fiction spawned an entire genre publishing industry. The letter columns in "Amazing", where fans could make contact with each other, led to the formation of science fiction fandom, which in turn had a strong influence on the development of the field. Writers whose first story was published in the magazine include John W. Campbell, Isaac Asimov, Howard Fast, Ursula K. Le Guin, Roger Zelazny, and Thomas M. Disch. Overall, though, "Amazing" itself was rarely an influential magazine within the genre after the 1920s. Some critics have commented that by "ghettoizing" science fiction, Gernsback harmed its literary growth, but this viewpoint has been countered by the argument that science fiction needed an independent market to develop in to reach its potential.