I find the whole yellow paint argument to be stupid. Back in the day, level design was so spartan, that if you saw a ladder, you could resonably infer that you could climb the ladder. Nowadays level design has become so rich in detail that you need a way to differentiate between objects you can interact with and objects that are just placed for fluff.
I have wasted so much fucking time in games trying to climb ladders that were just decor.
Is that comparable with the amount of time people spent trying to open walls in Wolfenstein 3D?
I used to love using the Wolfenstein 3D level designer to create a VR minesweeper sort of thing … all the walls are doors, but some of them release baddies in a controlled manner and others notsomuch >:-)