The devil's in the details. There's an enormous difference between "I'm going to use a dev-friendly way to manage and swap out all the different configurations

The devil's in the details. There's an enormous difference between "I'm going to use a dev-friendly way to manage and swap out all the different configurations that I might want to plug into the app while I'm testing it, but still plug them in using the same mechanism", which is basically what you get with dotenv files, and, "I'm going to configure with environment variables in production and JSON files in development," which is another thing I often see people doing.