AWS, Azure, and GCP are networking products with a billing system bolted on. VPC, VNet, subnets, route tables, NAT gateways, transit gateways, security groups, peering, BGP for hybrid cloud — every one of these is a Layer-2/Layer-3 concept that started in the OSI model. Cloud engineers without networking foundations hit a hard ceiling: they can spin up a VPC from a Terraform template, but can't explain why an asymmetric routing path is dropping their packets, can't troubleshoot a misconfigured BGP peering with on-prem, can't pass an interview when the question moves past "what is a load balancer". CCNA is the mental model that lets cloud make sense — and the credential that proves you have it.