Why wouldn't you specify the tech stack for new applications?
Do you really just ask the model to pick any backend stack and pray it works?
Not saying I do or I like it, but I suspect that is the trajectory. You don't ask the model to choose the backend, it's just not an important descision for someone looking to make a web app pop up in their browser. So at very least whatever the model picks will be the entry point for most people into software development.