If you only walk as far as is needed to get to your spot and then sit, a 9, 10, 11 lb gun is not that bad.
When you'll put on 10+ miles over rough terrain, there is a noticeable difference between a 7.5 and 9.5 lb gun. It's not that the extra 2 lbs is such an added load; It's a pittance compared to what many of us carry in packs on our backs or around the waist. The difference is how the rifle is carried. Slung over your shoulder and constantly pulling down on it, trying to slip off, upsetting your balance. A couple pounds there does matter. My hunting rifles are all in the 7.5-8 lb range with glass, add a little more for the bipod. No way I'd want to start out with a gun that weighed nearly 10 lbs and then add another 1-1.5.
I hunt all along the rockies on both sides, usually not below 9,000 ft. I live at 6,800 ft, so acclimatizing is a non-issue, but the increase in altitude lowers temperatures, and the terrain can be very challenging. Haven't been on many hunts that didn't involve negotiating steep, rocky terrian with ice and snow. I usually use large hip packs to try to keep my center of gravity low. I do not want a pig of a rifle throwing my balance off.
Sure, you can sling it across your chest to mitigate that strain-but then what do you do if you jump an animal?