I agree to all this!!! I'm actually trying to make sure my less educated sims not climbing to high on the career ladders, but it's of course not easy to keep track on all this. Wish it was controlled by the game, that grades matters! I guess they think that we should be able to tell whatever story we like, say a poorly skilled/graded sim by random luck becoming the mayor of the town. Still, this would still be possible if well skilled sims climbs faster, technically.