Are the developers of XIV out of touch?

[Berethos]

And don't tell me the namazu are flying the mikoshi with sheer willpower alone x)

Not when they are hanging on for dear life.

In-game explanation is of a similar bent to how the flying chair (made by Alchemists) works - enough Cloudsbreath added during construction (intended to make it easier/light enough to carry for the Namazu) had the additional effect of aspecting it enough to wind that it can fly.