Standard cells are a popular design style that makes layout generation easy. Layouts of basic gates such as AND, OR, NAND, NOR, and NOT as well as arithmetic and memory modules are provided as input. These cells are designed with similar characteristics, such as constant height, and can be manipulated easily to generate a layout. More on this later. Reality is more complex and a knowledge of digital circuit design will be important for some time to come.
Someone has to design and implement the module libraries.
A significant part of digital circuit design focuses on analysis of internal circuit operation. The library-based approach does NOT work for all situations, i.e. high performance designs like microprocessors. For microprocessor design, which push technology to its limits, this approach becomes less attractive. The abstraction-based approach is only correct to a certain degree. Digital Circuit Design Scaling tends to emphasize other deficiencies of the abstraction-based approach.