at least by the 1990s, the heat index was definitely something communicated pretty routinely in local news etc, at least in these parts. Not sure what you mean by "preferred narrative" aside from stating obvious facts about now versus in the past.
the 110-115 heat index numbers on back to back days is insane. I don't remember this combo of 100+ and 70-75 dewpoints anytime recently. The July 2024 extreme heat had dews in the 60s.