If builders built houses the way programmers built programs, the first woodpecker to come along would destroy civilization. - Gerald Weinberg

Things are the way they are because they got that way

Let’s hope that no system of theory of systems will ever eliminate the other systems – that no approach will be promoted to a dogma, and no group of scientists will become the high priests. Shouldn’t we rather let a hundred flowers bloom...?

We were doing incremental development as early as 1957, in Los Angeles, under the direction of Bernie Dimsdale [at IBM's ServiceBureau Corporation]. He was a colleague of John von Neumann, so perhaps he learned it there, or assumed it as totally natural. I do remember Herb Jacobs (primarily, though we all participated) developing a large simulation for Motorola, where the technique used was, as far as I can tell, indistinguishable from XP.