Let the platform do the heavy lifting and let your developers focus on delivering value, in the form of good application code. Deployment and infrastructure is just an unnecessary distraction. Remove that cognitive load and your developers will thank you for it in the long run.

Having 25 years experience working in Ops for software companies, I've become an advocate of Platform Engineering, Internal Developer Platform products, and maintaining some separation of concerns between building and running.

What inevitably happens is that application engineers' cognitive load goes through the roof trying to understand how to write good code, deploy it, and then support it in production; hence the need for specialist Ops engineers who understand how to deploy and operate applications in production.

Build and run is a nice idea but it's very hard to do successfully in practice. Once a feature-focused application team has released their software, their product managers typically move them onto the next shiny new feature. The application engineers attention is not on running the feature.

No. Is the answer. Not if you really care how your applications will run in production. Whilst IaC makes it relatively easy for engineers to deploy their code to the cloud, it doesn't automatically make the right decisions about how it should be implemented within the broader ecosystem.