The underlying theory is that to create successful software, the team must have a clear understanding of the goals and motivations of the stakeholders.
The ultimate goal is to produce software that is highly consumable and meets or exceeds the needs of the intended client.
While the following four groups are unique however there can be and is usually a lot of interaction between them: It is crucial to speak with all stakeholders, even if they are not the primary audience of your software.
By identifying your stakeholders properly and soliciting helpful feedback early on in the development process, agile and outside-in methodologies can mesh together seamlessly.
They cite the lack of enthusiasm by developers as the main reason to not implement sweeping, large scale change.