Why is 'overlayering' discouraged in Dynamics 365?

'Overlayering' refers to the practice of modifying the standard application code directly, rather than using approved extension methodologies in Dynamics 365. This practice is discouraged primarily because it may lead to upgrade challenges. When organizations opt for overlayering, they create a situation where custom code is tightly coupled with the standard codebase, making it difficult to incorporate updates and enhancements available in newer versions of the application.

As Dynamics 365 evolves, any modifications made through overlayering can conflict with system updates or require significant rework to align with the new versions. This not only hinders the seamless upgrade process but can also lead to increased maintenance efforts, system errors, and operational disruptions. Adopting best practices such as extensions allows for more modular, easily maintainable customizations that do not interfere with the core application, ensuring smoother updates and a better long-term strategy for managing changes and enhancements.

While some might perceive overlayering as a path to easier customization or as a more efficient method, these advantages are quickly overshadowed by the significant challenges introduced when trying to keep the system current and functional with each upgrade cycle.