Quote Originally Posted by Merudo
Is that because a wet-sump engine doesn't give the oil a good enough chance to cool down enough, as it's still right there, being constantly soaked with heat?

Yep, though I think even if you added a good oil cooler to a wet-sump engine it still wouldn't cool as well as a dry-sump one. The reason being that the oil is removed from the sump so there's not that big mass of oil to heat-soak as much.