No. No. They don't have to. You don't have to make a high-level party fight on a greased rope to be level-appropriate; that doesn't even make sense unless you want to separate out the rogue-type (and unless nobody else can fly of course) – otherwise what you're doing there is adding an additional complication to a fight to make it harder, by forcing nonspecialized characters to make basic skill checks.AllisterH said:Actually, I would disagree and state in fact that most skills do scale with level in that skill encounters become more dangerous AND the use of opposed checks.
Even many opposed skill checks don't meet meaningful opposition – use rope vs. escape artist being a big one, bluff vs. sense motive; on the other hand spot/listen vs. hide/move silently do scale very frequently. It depends on the skill really. But there's no special reason that all skill checks have to scale in 3e. "Designer intent" doesn't count.