Go to a place where it's sunny all the time. Then go to somewhere where it's cloudy all the time. You'll notice the difference when looking at older people's skins. So hydration and sunscreen are for sure helpful. All the other aging stuff... Dunno, but I think at least some of them are.
Reminds me of when I used an anti-wrinkle cream as a hand cream once. It anti-wrinkled the skin on my knuckles, so making a fist, the knuckle skin went so tight it started to tear.