@chris I think a lot of it is psychological. I'm sure there are tons of cabs that sound great with all the amps, but there's that mental factor that has you questioning if the sound you're hearing, even though it may be good coming form 1x4" speaker, couldn't be better if it were coming from the
actual cab that went with the amp. We hear tone with our eyes and judge tone based on what we
think should be the correct configuration. So you're right, but the psychological aspect can't be ignored, no matter how immaterial it may actually be in a technical sense.
Interesting thing to note, too, is that I did end up taking a poll on the Helix page and the "amp+cab" block got the fewest votes by FAR. I think, though, in a way it's not fair since you can only have ONE cab, which cripples things if you're going for a bigger, stereo sound. It's a good starting point but it pigeon-holes you into only using a single mono cab. In any case, IRs and multiple cabs were the most popular.
not sure exactly your point.
but i'll say this: back in the Ultra days. i once made 2 recordings, one called Real Amp, and one called Axe-Fx. i played them back to back and had people guess which was which. after a bunch of guess were made i revealed the answer.
i said Recording 1 was the Axe, a Mesa amp, and Recording 2 was a real Diezel VH4 through a Diezel 2x12 cab.
comments followed like "see i knew i was right" and "yeah of course Rec 2 is the real amp because of the smooth high end, it just sounds more real" etc.
then after a bit i said "OH NO. sorry everyone, i mixed up the recordings and it's the opposite! Rec 1 is the real Diezel, and Rec 2 is the Axe mesa."
no shock to me, the same people who were like "yeah i knew what i was talking about" suddenly were saying "ohhhhh yeah i KNEW that Rec 1 was the real amp because of the high end fizz in Rec 2." basically the opposite of what they just said earlier.
so much of audio and interpretation is linked to what our eyes and mind believes. if you tell someone THIS WATER IS HOT! and put their hand in it they go OMG OWWWWW even though it's cold water. if you tell someone "wow this strawberry ice cream is amazing!" they think it's strawberry at first even though it's raspberry. these things have been proven time and time again.
it's no different with audio, and people can fool themselves into thinking whatever they want regardless of how obvious the reality is.
some of us here try to part the clouds with years of experience and explaining these concepts, and (no real fault to them) many people just don't believe us and tell us to get a life. then after some time, they first-hand experience what we were trying to tell them, and they're like wtf. *shrug* par for the course.
people can believe what they want and request features to make things easier or faster. but some of us keep saying the same things for years because it's true. we all learn at our own pace, and it is what it is. as i said earlier, ideally people want to turn on the axe, spin one dial and instantly have a "good" tone that sounds exactly like Metallica, or Larry Carlton, or U2, or you name it. if it was really that easy, we would have had it by now. we're over 10 years into the Axe-Fx gear, FAS is really good at this. yet we don't have an instant "sound like ___" button yet. there must be a reason.