I understand what you're saying. You're definitely not wrong. I'm getting a CF shaft. My FargoRating is 650. I'm not going to jump 100 points overnight.
However, it's not always that simple. I live in Texas. It gets to be 90+ degrees at least six months out of the year. Unless you always remember to get your cues out of your car, they will wear fast. Hell, my shafts would warp in New York where they would *never* see the trunk of a car, nor temperatures over 95 degrees. Carbon Fiber is a superior material that's going to keep its straightness under harsher conditions for a longer amount of time, possibly a lifetime.
That lack of variance helps. Will it help a novice? Will it be better than a *new* and high quality wood cue? Probably not. Novices miss for many reasons that have nothing to do with the fractions of an inch improvements carbon fiber offers. Hell, we can say the same thing about most high ranked amateurs, and even some professionals. But, the latest and greatest *is* better. I can't say if it will produce the greatest game of pool ever played but I do believe it will minimize equipment defects that could cause misses.