The set of (say) 4 motors consumes much more power than the on-board computers. Brushless controllers these days handle 20 amps at around 5 volts for a total wattage of 400W(!) . The on-board computer power doesn't even count.
Of course, you're right that powerful computers are needed. But it's more about miniaturization for weight purposes.
Of course, you're right that powerful computers are needed. But it's more about miniaturization for weight purposes.