Well with the airship its not like you got stuck permanently or gained anything from doing it, so its technically not an advantage, with those rocks it is.
So how/when those rocks disappear is really the question. They look fake, just like the rest of the appearing/disappearing objects in FFXI, so there must be a trigger.. of some kind. Maybe wind weather since wind normally erodes structures such as that? I doubt anyone will care enough to actually go and find out, seeing as you still need to figure out the miasma timing
Idk what rocks you are talking about. If the following conditions are fullfilled :
- The miasma Wall that is right at the bottom of the path to climb the mountain (like 5 sec away walking) is open
- The luminant is behind that wall
Then reaching the top is "quick" and it's actually the quickest possible way to reach the top, because the luminant is like ~10s from the start of the climbing path which means the only thing you have to do is climb the mountain in less than 1:15s. The main issue will be timing the time at which you click the luminant so that the 3 walls that can block your way on the way up don't pop. I'm sure it's possible, but you'll definately need flee speed 100% of the time.
There's a path with boulder blocking the way on the west(?) side, you can get around it using flee and practice. Also once in a great while luminant will appear next to this path.