Capgemini argues that using multiple databases improves the ability to unlock business benefits from data by allowing for a more flexible and tailored approach to data analysis. The company suggests starting with one database that partially meets all analysis needs, then adding other databases such as graph or NoSQL to address specific bottlenecks. This approach can help achieve faster query performance, improved productivity, increased insights potential, and better governance, while also mitigating the costs of increasing IT spend, integration complexity, and requiring diverse skill sets. However, it's recommended to work iteratively, starting small, and adding databases as needed to test performance needs and justify the use of additional technologies.