I'm doing a true ultralight build right now. Steel since it's lighter than carbon for a barrel. It's for when I'm packing it far and or up mountains.
If I'm going to largely be sitting somewhere and not have to carry it that much, then somewhere in the 9.5lb range seems nice. It's easier to shoot and offers a more sturdy platform for those rare really long shots.
But for me lightweight is about actually being there. Still having the drive to go one more drainage over. Shooting the animal is by far the easiest part of hunting. Light rifles don't hinder it that much. If we're honest, we can all go way down in caliber/energy for what we shoot for 99% of shots. That mitigates most of the recoil and harder to shoot problem.
If everyone limited themselves to nothing more than 308 win muzzle energy, at least in NA, there would be almost the exact same number of dead animals every year. Probably more.