The article goes on to talk about Jsonnet, which takes the exact approach you describe - it generates JSON by aiming to be a "templated JSON" where the templating involves generating semantic objects, not strings.

Here's an example (adapted from some real-world code) where I specify the k8s cpu limit in one place, and then look up that info in several other places to avoid needing to change multiple values later:

    {
      local container = self,
      requests: {cpu: 5.5, memory: "2G"},
      limits: container.requests + {memory: "4G"},
      environment: [
        {
          name: "NUM_THREADS",
          value: std.toString(std.ceil(container.requests.cpu)),
        },
      ],
    }

Note how I can patch the container.requests object with an alternate memory limit, and how I can calculate an expression for the NUM_THREADS value in order to automatically set it to ceil() of the requested cpu.

(edited for nicer formatting of the code)