I'll agree with that, definitely. Unfortunately, the law of unintended consequences applies. Being good at flying and/or not forgetting how to fly does not necessarily mean getting a good NSS. There is a disparity between flight grades and simulator grades which means that, for all students in all squadrons, an incomplete flight mathematically translates into a lower NSS on average because flight grades have higher MIF standards than simulator grades. Hence, every incomplete flight will lower your block mean % score unless you were horrible at the early block simulator events, and a lower mean % score translates into a lower NSS.If you get a lot of incomplete flights due to weather, it may also be because some of your IPs care about getting you into the cockpit so you can actually continue learning to fly instead of sitting on the ground for another day and forgetting how to fly.
This discrepancy leading to a lower NSS for incomplete flights is further compounded if you are in a lower-grading squadron than one which tends to grade higher. To find out which squadron is which, ask a sample of students who have completed Contacts how many 5's they got for the whole block. If they got so many they can't remember, they might be Chuck Yeager reincarnate or they are in a high-grading squadron.
This doesn't really matter so much for students because it's just another aspect of their NSS that they have no real control over. It's just another one of life's little unfairities.