One could argue that the most important person or role in a software development project is the customer. The customer is ultimately who decides when a project or a feature is finished and when the quality is acceptable. Yet historically, involving customers in projects has proven to be problematic for various reasons. Often it is hard to get the customer to allocate enough time to actually participate in meetings and sprint demos. And when customers are included in the process, they often start participating too late, usually when it is time to start doing the acceptance testing. By that time all the decisions have already been made and changing the underlying requirements at this point often costs a lot of time and money.