This is drummed into students during the motorcycle training syllabus here (Sydney Australia) - "Do not ride beyond your field of view. It you can't see beyond a curve, crest, fog, rainstorm, queue of traffic or whatever - make sure you're going slow enough that you can stop before you get to the end of where you can see".
I always explain it to friends starting out "you need to assume that just around every corner there's a stationary shipping container that's fallen off a truck. If you cant stop in time by the time you see it - it's your fault for going too fast."
Many people don't seem aware that the reduced speeds at curves aren't because your car can't take the curve at that speed (most can) but because you can't tell if there's an obstruction from a sufficient distance.
I always explain it to friends starting out "you need to assume that just around every corner there's a stationary shipping container that's fallen off a truck. If you cant stop in time by the time you see it - it's your fault for going too fast."