There is a darker, more sinister issue at stake.

I have it on good authority that there are more than a few women who find it necessary to wear panties or other undergarments due to the near-constant, albeit slight, production of feminine fluids. This is not due to disease or infection, it's just how they get things done. "Discharge" can be a symptom of disease, but disease will not be addressed in this writeup, because it is icky.

The vagina is a tidal place, but the tide is always going out. This is what keeps our insides clean. Think of it as vaginal saliva. Some girls have more than others, of course. Hormones, personal habits, hydration, genetics, arousal, exertion...these will all affect the level, and quality, of the dampness.

To put it bluntly, the physics of pants/skirts can produce a highly disconcerting effect, wherein your precious bodily fluids are deposited on your clothing (unhampered by those dear, dear panties) and suspended away from your body long enough to either cool down or dry up. Woe to thee as soon as it becomes necessary to sit down. That scratchy crust or worse, cold goo will make you wish fervently you hadn't decided to be such an Underpants Rebel.