People with low grimoire score that I run into seem to know less about the game in my experience. It's kinda funny tho because I was playing with a lvl 31 with a low score because I was gonna help him with nightfall and he said to me "Oh! You can't wear two exotics at the same time! I did not know that!" It only surprised me cuz its not like he was super low lvl. He also thought that you could choose what strike you wanted to do as nightfall, lol.