The models aren't writing new applications in C# unless you direct it to.
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.