In 1981the Burning Chrome anthology published a short story by William Gibson called The Gernsback Continuum. In this story a photographer, overwhelmed by images of a future that never came to pass, slowly begins to slip into an alternate continuum (Or madness) - A history based on all those alternate tomorrows of the past, the Popluxe atomic future of the 1940s and 1950s, all torpedo-rocketships and mile-high Art Nouveau towers. Overcoming his fears he begins to embrace this reality, until he encounters the natives of this Gernsbackian alternate future, a pair of whiter than white Aryan Americans. The sterile mindset of these Gernsback Continuum inhabitants sends the protagonist racing back to the safety of his continuum of origin, embracing pornography and news of crime to drag himself back to reality. He feels himself lucky to have escaped this pseudofascist white Gernsback-reality, with its implied holocaust carefully hidden beneath a veneer of giant airships and utopian idealism.
Which is all a bit odd, given that Hugo Gernsback was a Jewish immigrant who didn’t become a naturalized US citizen until he was in his twenties and who worked in publishing, one of the most notoriously vice-fueled industries the US had to offer at the time. He worked in electronics importing for a while, got into publishing magazines and catalogues for that industry, and discovered that he would rather print stories about scientific adventures than publish wiring diagrams. Hugo gets blamed for a lot in science fiction, even or especially the things he had nothing to do with. But Hugo Gernsback did create science fiction, so some of the blame of the genre must fall on him.
Mary Shelley didn’t write science fiction. She wrote an allegory about the responsibilities and failures of parenthood, disguised as a tale of horror and drawing influence from the medical science of his time.
Jules Verne didn’t write science fiction. He wrote adventure stories that focused on extreme engineering projects.
Edgar Rice Burroughs didn’t write science fiction. He wrote action stories set in exotic locations filled with beautiful princesses and ancient ruins.
Science fiction is a genre, and genres are marketing categories. Hugo Gernsback created the genre of science fiction. He worked in publishing, liked stories with lots of engineering detail and interesting gadgets, and liked to play with extrapolating current technical developments into the future. He invented the marketing term ‘science fiction’, along with his preferred clunkier term ‘scientifiction’, to describe the works he enjoyed and wanted to publish. Gernsback founded Amazing Stories, the first magazine devoted solely to science fiction, specifically to publish the sort of stories he enjoyed. He also encouraged his readers to get in touch with one another to discuss stories and share ideas, and the first SF fandom came out of those contacts. That fandom grandparented Shelley and Wells and Burroughs into the genre after the fact. Hugo Gernsback promoted a specific form of scientific storytelling, invented a literary genre to sell those stories under, and pushed the creation of a community to read and create those stories.
Naval adventure stories set in outer space are science fiction because Hugo Gernsback said so. Medical thrillers based on cutting-edge biosciences research are science fiction because Hugo Gernsback said so. The consensus-future of science fiction looks like Fritz Lang’s Metropolis because Hugo Gernsback said so. Advanced societies are full of bureaucrat-ordained names like Ralph 124c 41+ and Jor-L and 0B1-KN0B because Hugo Gernsback, born Hugo Gernsbacher, said so.
He also ripped a lot of people off. Pretty much everyone he worked with, really. This is hardly surprising, given the state of pulp publishing in his era, but that did make it easy for John W. Campbell to dominate the new SF publishing field just by being somewhat less awful than the blatantly crooked Gernsback.
Hugo Gernsback published the first stories of a Russian Jewish immigrant, an anarchist feminist woman, and a formerly-suicidal gay teen on the verge of dropping out of college, all of whom became major figures in science fiction. In the 1970s Brian Aldiss accused him of lowering the literary standards of the genre. In the 1980s one of the new luminaries of the deliberately reactionary sub-genre of cyberpunk blamed him for the all-white authoritarian future of John W. Campbell. Today he’s mainly dismissed as a crook who mis-ran a lot of magazines.