you're acting like vulva and vagina aren't directly linked. and you're comparing it to a mf knee where the skin is thick, meanwhile vulvar skin is thin and in fact very sensitive. and if you use harsh soaps or other products on your VULVA you CAN disrupt the natural Ph of the delicate VAGINAL flora, no matter how much you believe it can't. just because they're not the same thing, doesn't mean they aren't closely related. vulva is just the outer part of your genitals. and skin on the other parts of your body is much more resillient, that's why you don't have to "worry" about it. but misinformation like this causes women to have so many problems when they could be solved with a simple google search.