The article discusses how denormalization can be problematic in OLAP scenarios and slow down queries. It suggests using ClickHouse dictionaries to optimize data retrieval by reducing the need for reading and decompressing redundant data from disk. The author demonstrates this with an example of a weather dataset, showing that normalizing the data and using dictionaries can significantly speed up query times. They also highlight how denormalization can complicate queries and emphasize the importance of optimizing database structures for better performance.