That feature had to be added for crossplay to work IIRC (I think it explained it in the crossplay FAQ?)
I’m not suggesting that it’s hard to implement (I’m not going to speculate on how easy/difficult it is either, since I’ve got no idea what FS tools and processes look like), just that it wouldn’t be worth the time in the absence of demand
EDIT: Ah, it was a “may be needed to change your username”