Genuine question: How are we sure
that they're not illusions? And if they aren't, why wouldn't the 'lore' fix just be to make them illusions?
Mechanically, they're not SO far removed from the Simulacrum spell to be a breach of D&D rules in principle. Sure, Simulacrum is usually copying a person, and a caster can't usually maintain more than one, but it's not tough to imagine those limiting factors being abridged for a more powerful creature.
