Five years ago, Customer Data Platforms (CDPs) emerged as an all-in-one solution for collecting, unifying, and activating customer data, but they failed to meet the needs of most companies due to rigid data models, long onboarding times, and redundancies with other analytics and marketing tools. Now, the modern data stack and data activation have given companies access to best-in-class solutions for each component, leading to the rise of Composable CDPs as a more ideal solution for data-forward organizations. A Customer Data Platform is an all-in-one platform built for marketing teams to collect, transform, and activate customer data, but it has limitations, such as duplicating existing data and not being able to replace traditional data warehouses. The modern data stack already provides components of a CDP, making it possible for companies to turn their existing data platform into a Composable CDP by adding the data activation layer. This approach allows companies to leverage best-in-class tooling from their existing data platform, providing a true single source of truth for customer data, flexibility, better data governance, and future-proofing by design. The future is moving towards warehouse-native solutions, with data activation and reverse ETL democratizing access, positioning the data warehouse as the system of customer record that powers business operations.