You know you can also use the heroku build packs on fly.io right?
Or do you mean it's the same in Fly.io? If it auto-detects Node.js (through package.json), or at most allows for a dropdown to say "Node.js project", then that sounds about right for me.
Indeed the docs[1] say Fly automatically detects a Node.js project, so you don't need to create a Dockerfile.
[1]: https://fly.io/docs/languages-and-frameworks/node/#launch-th...
Well it still creates a fly.toml for you, which is still a new config file that I have to maintain across projects.
I mean it even creates the basic file for you, I'm not sure what the issue is?