Horror comics have always been the rebellious cousin of the superhero genre. Historically, it took time for superhero comics to become as popular and as important as they are today. In the 1950s, during the Silver Age of comics especially, the Comics Code Authority and other censorship entities would neuter the creative freedom of superhero, fantasy, war, sci-fi, and most anthology comics of the era.
The censorship authorities of the era could not do that with horror. Many horror publishers of the era refused to back down. Still, the Comics Code Authority would create publishing standards for protecting young readers that made horror comics depicting gore and horror unable to operate.