That's only true if you reward players exclusively for combat rather than social encounters.
In a previous campaign, my druid encountered some kind of Earth fey with an interesting looking magic pipe. While I could have just beaten him down and taken it, that character was a nice guy and therefore wouldn't do that. We talked, and not only was my druid able to convince the fey to trade his pipe (I think it was in exchange for some gems) but he also taught my druid to wildshape into a statue. I got XP for the encounter, the magic pipe, and a cool new trick. While I could have gotten the first two by going all murder hobo, I would have lost out on the third. The reward was actually better because I chose the diplomatic approach. As an added bonus, I felt that I had real agency in the world, since my character was able to take an uncertain encounter and make a new friend.