AWS connectivity services allow customers to create and run different network architectures in their accounts. VPCs have been instrumental in allowing organizations to scale application deployments and allow for secure design patterns when it comes to migration of their on-premises services to the cloud.
A key factor is the ability to provide connectivity in a scalable fashion between applications running in the cloud and on-premises data centres. Before Transit Gateway, customers used VPC peering or Transit VPCs (which also require extra network devices) to create a mesh topology. Neither solution was scalable and this limited the ability to provide connectivity to on-premise data centres, especially as the number of VPCs grew.
