See the bold? With a shorter course, perhaps on some of the bad tee shot holes, you wouldn't be hitting driver and would have been "safe"...and on the duffed chips, you may have been hitting a wedge to the green instead of a 6 iron, and would have been putting instead of chipping. Length can definitely affect it more than you think.
Here's the thing, My score was basically the same as it is on shorter courses if I did the same things wrong. I rarely, if ever, hit something besides driver on a hole that's 300+ yards unless it's a forced lay up because of a dogleg or hazard.