It's from the wishy-washy everything's-between-your-ears folk. They believe that words have an innate power, or something like that. By calling a scar "beautiful", it should become less of a burden. Never mind that by the same logic, calling ugly things beautiful would make true beauty look drab. One wonders why they didn't think the tumor was beautiful.
It is only your straw-people that propose this kind of relativism. This was about gaining a perspective for appreaciating scars, as they carry memories. It is pointing at the beauty of scars. It is not inverting the meaning of the word, but aiming it at something thus far hidden. The fact that some scars for some people carry heavy trauma does not defeat the point in question.
Also, don't forget that there is no objective criterion for beauty - it is a judgment call. Therefore it is also mediated by language. Even if you correctly see that changing words does not on its own change the world, you are shooting past the target in denying that they have any unique power.