Well, if I was a typical consumer, I just don't think I would be in the market for an XS. I would be looking at the XR. So, I am looking at the comparable options 3 years ago....from a typical consumer's perspective. If I wanted a big iPhone 3 years ago, a typical consumer would have bought the 6s plus.
The problem is that the XS is really not comparable to the prior offerings, since it has OLED display, multiple cameras, stainless steel construction, etc... I really don't see it as an everyday consumer product. The 6s plus was a consumer product for folks that wanted a bigger display.
It is kind of like you can't really compare the iPad Pro with the iPad Air 2 (which was the flag ship before the pro). It is more reasonable to compare the 2018 base iPad......which is more of an everyday consumer product.
However, I do see your point that the introduction of these various product tiers (consumer and "pro") confuses matters.
If you were buying the XR as a typical consumer, what would be a better comparison from 3 years ago? The reason this is important is that prior purchase prices set expectations with many consumers. Especially, those folks that don't endlessly scan tech sites and fixate on specs.