In many settings, Half-Elves at the least aren't in the same situation as mixed-race people IRL. Hell in some you have some who are and some who aren't. Like, in Taladas, an Armach-Nesti Half-Elf is very much in that situation, but a Tamire Steppe Half-Elf isn't having the same experience at all, because he's part of a culture that's mostly Half-Elves (and a large and successful one). So this demand that every person playing a Half-Elf must be interested in that narrative seems strange and bordering on the repugnant. It's like demanding every Dwarf player be telling a story about hearth and family, or every Halfling has to be a story about how they left home and are unusual for adventuring. Like one-true-wayism for how you play a race, but only applied to certain ones.