I think it was an artifact of applying physical construction project concepts to building software.
If you're building a house, or something bigger, you don't just start nailing lumber together. You have a blueprint. Pretty detailed, and it uses industry-standard terms and markup. Any builder can take it and use it to construct the building. It has the dimensions and specifications for the foundation and all the rooms. It has considered where the rooms are, which walls are load bearing, where the staircases and HVAC and plumbing and electrical runs are, where the windows and doors are, pretty much everything. An engineer has signed off on the overall design as being safe and meeting all the applicable codes. You can order a list of supplies based on this plan and you'll be within a few percent of what you actually use.
Some small changes were allowed. You could change finish details like what style of cabinets or trim or door knobs would be used. But you could not really approach the builder once the framing was complete and say actually I wanted the living room over there and the bedrooms over here and also I want to add a third storey. You also didn't build one bedroom, and then based on that experience extrapolate the design for the next one, and then apply that to building the kitchen, and so on. It was all done up front.
People, especially people who were used to managing physical projects, thought that with the same level of planning, and the same approach to management, the same results could be achieved in software projects.
If you're building a house, or something bigger, you don't just start nailing lumber together. You have a blueprint. Pretty detailed, and it uses industry-standard terms and markup. Any builder can take it and use it to construct the building. It has the dimensions and specifications for the foundation and all the rooms. It has considered where the rooms are, which walls are load bearing, where the staircases and HVAC and plumbing and electrical runs are, where the windows and doors are, pretty much everything. An engineer has signed off on the overall design as being safe and meeting all the applicable codes. You can order a list of supplies based on this plan and you'll be within a few percent of what you actually use.
Some small changes were allowed. You could change finish details like what style of cabinets or trim or door knobs would be used. But you could not really approach the builder once the framing was complete and say actually I wanted the living room over there and the bedrooms over here and also I want to add a third storey. You also didn't build one bedroom, and then based on that experience extrapolate the design for the next one, and then apply that to building the kitchen, and so on. It was all done up front.
People, especially people who were used to managing physical projects, thought that with the same level of planning, and the same approach to management, the same results could be achieved in software projects.