The human component of a system matter a lot, and there is a point at which it may have troubles scaling up, because is something that doesn't scale so well as

The human component of a system matter a lot, and there is a point at which it may have troubles scaling up, because is something that doesn't scale so well as computers and technological resources. And a part of designing an scalable system is taking the human side into factor, the cognitive load on people that should make it work and keep it in that state. The complexity of a system, the different roles, data flows, non-standard configurations, exceptions, the use of pets instead of cattle, how things are interrelated, knowledge bases and so on are topics that should be taken into consideration. This is a related problem with what is discussed in The Mythical Man-Month, is not about building a program, but keeping a complex system running and evolving. And to make things worse, you can put another identical computer and handle twice the load. But people are not identical, and not just in knowledge that can be written down and transmitted but in different skills and areas covered.