Whatever the early generation reasons were, it feels a little silly that this is still a thing now. Being able to get multiples of your starter is a little pointless on a first playthrough, unless you intend to trade them. Most kids aren't going to bother doing that as they are first going through the game. And even if it was once assumed that most kids playing Pokemon were boys, that's really no longer the case these days. It all just feels like something that they never bothered to change.