It's not a tautology. That you can go out tomorrow and buy a deluge of computers with different hardware and run the same software without change is exactly a demonstration of substrate independence.
And if one of those computers failed, it wouldn't classify as a (proper) computer.
You can move your pointer anywhere you'd like, it is ultimately tautological. Infinite regress is a bitch lol
Say, have you taken into consideration the role consciousness and culture are playing here? Like this "reality" you are describing, do you know what the actual, biological/scientific source of it is? :) But now I'm kind of cheating, aren't I...I think we're not supposed to say that part out loud! ;)
https://www.edge.org/response-detail/27126