Ossification. The same thing happens with laws and regulations. It moves the knowledge and activity from one of expertise and judgement to a ruleset. Changing a

Ossification. The same thing happens with laws and regulations. It moves the knowledge and activity from one of expertise and judgement to a ruleset. Changing a ruleset is hard because you have to play within the bounds of the other rules (which may include rules for changing rules). The expertise in the ruleset also falls away over time as people become increasingly reliant on the software system. Eventually the software becomes the definition of the rules, and any changes to the rules have to be changes that someone today can figure out how to implement. If they can't implement it, the rules can't change. Then you get a big-bang rewrite because everyone is frustrated (or they move to SAP, and are frustrated for other reasons). The rewrite neglects a bunch of edge cases already accounted for in the old system, it takes a decade to finally retire the old system (hopefully), and then in another decade they repeat the process because the expertise is, again, lost.