There's a recurring theme in this thread that "bikepacking" is a new term. It isn't. It's just being used differently now. Cannondale used the term "bikepacking" in their catalogs when they first started making panniers in the early 70's. In fact, their panniers were originally called "bikepacks". See, for example, the 1973 catalog here:
https://vintagecannondale.com/year/1973/73summer.pdf
For whatever reason, the term didn't really catch on until people started using it more recently.