Yes, that isn't part of regular cruise control. It's called "cruising", not "driving in traffic". These systems have been around since the 60s, far longer than automotive sensors have existed.

The part where the car actually responds to the movement of cars around them is a new thing (only available for ten years or so), and is called adaptive cruise control.

As I said cruise control doesn't have to have active braking because as you point out cruise control predates active braking. To me its analogous to a graphics card in a computer, a computer doesn't have to contain a graphics card, after all the computer predates the graphics card. Nevertheless you wouldn't argue that a graphics card in a computer isnt part of the computer.