I believe it's more sinister than that: it's to prevent the people who are working on the project from sleeping at all. Remember, most developers are on a salary, which means minimum 40 hours a week, but a maximum of 168. People who view other humans as expendable "resources" - the amoral types who inevitably rise to prominence in corporate America - then see planning as a strategy to push that number as high as possible. They thus insist that an inherently unpredictable process - software development - must be 100% predictable and, when that inevitably turns out not to be the case (yet again), they demand punitive uncompensated overtime. This isn't an accident.
I believe it's more sinister than that: it's to prevent the people who are working on the project from sleeping at all. Remember, most developers are on a salary, which means minimum 40 hours a week, but a maximum of 168. People who view other humans as expendable "resources" - the amoral types who inevitably rise to prominence in corporate America - then see planning as a strategy to push that number as high as possible. They thus insist that an inherently unpredictable process - software development - must be 100% predictable and, when that inevitably turns out not to be the case (yet again), they demand punitive uncompensated overtime. This isn't an accident.