it's just a tautology stating that machine-id is indeed used
I stated two things, that machine-id is used and that adoption is high. You're ignoring the latter. Might be correlation or causation, but definitely not tautology.
You have not provided any rationale for why it's necessary aside from stating a tautological fact here
This is a gross misrepresentation of my words. I'm not saying it's necessary, I'm saying it contributed to the success of some of the most private distros that exist today. In other words a net positive. You provided zero evidence that it was a net negative, and demonstrated ignorance about the complexity of engineering.
Either you keep misunderstanding my argument, or deliberately misrepresenting it to avoid admitting its merits. It's becoming clear which is true.