I'm fairly certain that's what the deal is here with Fortnite, and yes, I agree, it's ridiculous making new emails addresses so you can make game accounts for kids, but that's what the market is doing. In order to have a second Splatoon account for online matches, I had to buy Nintendo Switch Online family plan subscription, and use my backup email address for a second Nintendo account. "one online account per unique email" is a paraphrase from Nintendo Support, and Epic Games is doing a similar deal with Fortnite.