i recently walked a friend through setting up a their MacBook Air M1. and, like you said, i told them to skip setting an Apple ID. that it was not necessary.
but the first setup doesn't allow you to skip. or didn't make it obvious how to do so. (dark pattern?)
i suppose one could use keyboard shortcuts, or install in safe mode, etc... but for the regular users won't be able to skip that step.
It does allow you to skip, and it is obvious.
There’s a screen asking you to log in to your Apple ID. There’s a button that says “Set up later”. When you click it, it asks you if you are sure. You confirm. That’s all.
Here are the screenshots:
While this is true (to my increasing chagrin), having an Apple ID in and of itself doesn't cost you anything. It does create an account that you can then tie charges to.
I don't, however, recall this quite rising to the level of what I'd call a "dark pattern"; IIRC when I set up my M1 MacBook Air not that long ago, the "Enter your Apple ID" had a "Skip this step" link that was pretty easy to find.
Privacy.
You can't get an Apple ID without an email and a phone number.
When you enter it during the machine setup, it ties that identity to that hardware serial, which maintains a persistent TLS hardware-serial-linked connection to Apple at all times, letting them know in what cities and at what times that phone number's owner is using their computer.