8/17/1942 Marlowe looks out a high window

August 17, 1942.  This date saw the publication of The High Window, Raymond Chandler's third novel about L.A. private eye Philip Marlowe.   (Has anyone else pointed out that his novels arrange the same way chronologcally as alphabetically?  Just like Sue Grafton's sort of.)

And speaking of the alphabet, this story features characters named Marlowe,  Murdock (two of them), Magic, Merle, Morny, and Morningstar.  Why do authors do that sort of thing?  What's wrong with the other letters?