[Annabeth frowns a little.] Because the Atrox are no longer a threat?

It's not a requirement so much as the whole monsters tracking our scent thing again. If you're just a kid without any training, it's a lot harder to survive, especially if you're still confused as to what's going on. The gods don't really involve themselves in their kids' lives, and we're mostly supposed to get to Camp Half Blood on our own. [Then there's a somewhat awkward pause.] Longer than most. The average age most demigods arrive is twelve, and most of the population is teenagers.