Takes a moment to moment mental load off so you can focus on the other cars around you better.
If the cars ahead of me are slowing down significantly I disengage and go manual until I have a better idea what’s going on.
My car can supposedly stop completely that way. I’ve never tried that, as it gets very slow (relative to highway) it’s willing to get way closer to the vehicle in front me than I am. I trust it (in theory). But it’s not worth testing.