I think you will find that tire diameter changes with tire width despite matching the profile.
I think you will find that that is absolutely correct, yet has absolutely nothing to do with what the guy you quoted, or myself, were talking about.
The guy you quoted was talking about tread depth, NOT tire profile. You then equated tread depth with staggered tire sizes, which are completely different.
You do realize that tread depth != tire profile size, right?