Anybody who says you can't climb them is either a [censored], or new to the series.
YOU CAN CLIMB THEM!
Not only have THEY SAID SPECIFICALLY THAT YOU CAN CLIMB THEM in podcasts, but that's also part of what the TES games are. You do anything, go anywhere, climb ANY mountain.
he said the opposite. he said the game world, though comparable in size to oblivion, will feel much bigger, partly because there are some mountains that you have to go around making some journeys longer. it was the game informer podcast. so i am guessing that some mountains will be scalable, some won't.