Information Technology, and the development of business computer systems, is relatively new, by which I mean less than 50 years old. I started in this business in the early 1960s and was involved in the replacement of punched card tabulator systems with punched card computer systems (such as IBM 1400s).
As the technologies grew more sophisticated (eg disks, bigger memories and compilers) so the systems we developed became much more complex. As the IT industry grew, so did the numbers of programmers, analysts and operators working within it.
These were mostly very bright people, skilled and inventive but with often little appreciation of the needs of business. The wheel would be reinvented countless times in many different ways and there were as many different ways of structuring computer programmes as there were programmers doing it!
It was out of this that system development methodologies arose. These early methodologies were often developed by the major hardware manufacturers and management consultancies and were intended to be templates for development. Some were good, some were truly awful. Some were concise and some, like SSADM, were massively...