The agile manifesto defines four values that the criteria for any method which calls itself "agile". I'm going to cover the ideas behind each:
Individuals and interactions over processes and tools
Back in the early days of mass-production, when companies like Ford were discovering the efficiencies of assembly lines, the theories of Fred Taylor were being applied in factories. These theories were based on the idea that complex jobs, such as assembling a Model-T car, could be performed by relatively unskilled and cheap labor if each step in the assembly line was broken down to a simple job that could be standardized. Workers were considered to be interchangeable cogs in a large machine.
Though “Taylorism” has been discredited, many management practices are still based on the idea that as long as a well defined process and set of tools exist, then the work that can be done by a group of people can be predicted and defined up front. Workers are considered “fungible” or replaceable and anonymous on a large project plan that attempts to predict what each part of the whole will take a worker to complete. Managers find comfort in this. As long as people and hours are are interchangeable, then we can play with the amounts of each to achieve predictability. This idea has been disproved for decades. It was the basis of Fred Brooke’s book “The Mythical Man Month” in the sixties. People and months are not interchangeable.
This is why agile values individuals and interactions over processes and tools. Teams of people make games. Artists, programmers, designers and testers all have to communicate to be the most effective. Collaboration and shared vision are key to great teams. Tools and process are still important, but they can’t replace this.
So why do we cling to this idea? Because it’s easier. Process and tools, interchangeable hours and people, spreadsheets that are meant to be crystal balls only require management. Collaboration and shared vision is harder. They requires leadership. Leadership is harder than management.