But Edward L. Stratemeyer (1862-1930) did exist and it was he who created Joe and Frank Hardy, along with literally dozens of other series characters in juvenile fiction.
Through his Stratemeyer Syndicate, ol' Edward would hire authors to write stories from his outlines. They got paid (poorly, in most cases) to write the texts, as well as agree never to reveal that they, and not the mythical Mr. Dixon, wrote the books.
Each new series began with three "seed" books, all released at the same time. If the first three books sold well, then others would follow in the series.
Ever hear of Leslie McFarlane? Maybe you haven't heard of him, but if you've read any of the first eleven books, then you've read his books. In his autobiography, Ghost of the Hardy Boys, McFarlane tells tales about his days with the Stratemeyer Syndicate. Like many Syndicate writers, he had done extensive free-lance fiction writing, as well as some newspaper reporting. While the quality of many of Stratemeyer's "hired gun" writers varied, McFarlane is generally considered the best of the lot.
According to James D. Keeline (Yellowback Library, No. 125, November 1994), McFarlane was definitely the writer of the first eleven volumes (see "The Hardy Boys 'Canon'"), as well as Volumes 16 and 17 (The Sinister Signpost, A Figure in Hiding),and Volumes 22 through 24 (The Flickering Torch Mystery, The Melted Coins, The Shortwave Mystery.)
Edward Stratemeyer died in 1930 and his daughters, Edna Squier and Harriet Adams, took over the Syndicate and continued the outlines. Edward apparently supplied the plot outlines for the first nine volumes.