AWS only allows 5 VPCs per region by default to balance the need for flexibility and the risk of overprovisioning. Here are some possible reasons:

1. Limiting resource consumption: By restricting the number of VPCs that can be created in a region, AWS can limit the resource consumption of each account and reduce the risk of overprovisioning. If each account were allowed to create an unlimited number of VPCs, it could lead to resource exhaustion, which could impact the performance and availability of other accounts.
2. Encouraging best practices: By setting a default limit, AWS encourages customers to adopt best practices for designing their network architecture, such as grouping related resources together in the same VPC or using a hub-and-spoke topology. This can help customers avoid creating overly complex and difficult to manage network architectures.
3. Promoting modular design: By limiting the number of VPCs that can be created, AWS encourages customers to design their infrastructure in a modular way, where each VPC represents a self-contained environment for a specific application or workload. This can help customers achieve greater isolation, security, and flexibility in their infrastructure.
4. Simplifying management: By limiting the number of VPCs that can be created, AWS can simplify the management of customer accounts and reduce the risk of misconfiguration or security breaches. It also reduces the complexity of the network topology, which can improve troubleshooting and reduce the likelihood of network-related issues.

Overall, by setting a default limit of 5 VPCs per region, AWS can balance the need for flexibility and control, while promoting best practices, modular design, and simplified management.

Summary:

• Limiting resource consumption
• Encouraging best practices
• Promoting modular design
• Simplifying management

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