The core secret of expansion solutions like Plasma lies in how responsibilities are divided. The underlying layer only handles one thing—ensuring security, performing data validation, and maintaining state integrity—nothing else. The application layer is where the real work happens; all business logic runs here. What are the benefits of this division of labor? The system won't be affected by changes in the requirements of a particular application. The incentive token XPL in the ecosystem is used to maintain network cooperation, motivating each layer to do its job well. In the long run, this clear architectural boundary leaves ample space for future expansion, and maintenance costs are relatively manageable.