Letting a new guitar rest - really neccessary?

Hi everyone,

we‘ve all heard that a brand new guitar should be left in its package, usually twnty four hours before playing. When googling for the reason, the answer was that the guitar, especially the finish, is sensitive to sudden changes in temperature and moisture. So far, so plausible. What I don‘t get is: most guitar cases (if there‘s any) don‘t provide good thermal insulation. The rapidness in temperature change should be more or less the same inside and outside of the package. For the moisture, the effect of the packaging maybe bigger, but i assume not bigger than if you open a window, turn on the ac, etc. depending on the room conditions. Surely you will have to retune the guitar, maybe a couple of times, but thats about it.

Has anyone of you ever experienced real damage because of not waiting before unpacking?