Because every software system is unique, the precise processes or procedures within each activity can hardly be defined.
[3] When computers were extremely large, expensive, and bulky (mainframes and minicomputers), the software was often bundled together with the hardware by manufacturers.
If business software needed to be installed on an existing computer, this might require an expensive, time-consuming visit by a systems architect or a consultant.
Such flexibility led to the rise of continuous delivery as a viable option, especially for less risky web applications.
The complexity and variability of software products have fostered the emergence of specialized roles for coordinating and engineering the deployment process.