I think this is really similar to the "we use kubernetes so we don't get locked into AWS" argument; true in theory, never pans out in practice. I'd hazard that

I think this is really similar to the "we use kubernetes so we don't get locked into AWS" argument; true in theory, never pans out in practice. I'd hazard that the number of engineering orgs using a single Terraform "stack" (repository? domain? whatever) to manage resources across multiple providers is in the single-digit percentages. The ability to transfer knowledge has non-zero benefit, but the reality is; that knowledge is 10% "Terraform & HCL", 90% "AWS Resource Configuration & Best Practices". 90% of it doesn't transfer, and most of the remaining 10% could be learned quickly enough. Maybe it enables you to transfer CI/tooling between cloud providers should your org switch. Probably the most reasonable argument. I think the core of what you're saying is actually right, for the same reasons that the kubernetes statement above is right; AWS is really becoming its own isolated world. Terraform on AWS makes less and less sense, as their in-house options like CF, CDK, SAM, etc evolve maturity beyond what TF is capable of. TF (and Pulumi) (like Kubernetes) is for everything else.