Publishers routinely reject things simply based on presentation for the simple fact that most authors are willing to do a significant amount of the work (that w

Publishers routinely reject things simply based on presentation for the simple fact that most authors are willing to do a significant amount of the work (that would otherwise be done by typesetters and editors) just to ensure they get published, and it's rarely going to hurt the publisher if the author takes their work somewhere else, instead. My theory for the mass use of the double space is that it was such a common requirement from publishers at one time (and in some areas probably still is) simply because it distributed a massive amount of menial work and most people can simply make a habit of it and never bother to question or complain about it. Another is that, once taught this particular practice, many people confuse it with the requirement that a document is double-spaced.