Within Amazon, the "Two-Pizza Team" principle emerged in the mid-2000s: team size should be limited to what can be fed by two pizzas (5-8 people), and each team independently owns and deploys its service. This principle became the seed of microservices architecture.
CloudFormation faces the same challenge. A single template with thousands of lines exceeds the scope of "one team understands and owns everything." We need a way to separate IaC by team boundaries, safely share information between teams, and deploy standards across the entire organization. Nested Stack, Cross-Stack Reference, and StackSets solve this problem