LLD Design Patterns: We Learned SOLID—So Why Are We Talking About Design Patterns Now?

The LLD Design Patterns series examines why developers need Design Patterns despite knowing SOLID principles and Object-Oriented Design. While SOLID principles improve designs and provide a foundational philosophy, they do not eliminate every design problem. Many developers treat SRP, OCP, or DIP as checklists rather than a philosophy. Consequently, understanding what SOLID was intended to solve is essential before transitioning into Design Patterns, as these patterns are not merely advanced OOP but solve distinct architectural challenges.