Some of the grimoire such as salvage and skirmish wins take time and can't be done if your bad IMO. Sure you can grab like 4500 worth of ghosts but the top tier grimoire score players (say 4800+) are usually pretty good I've experienced. When I enter a PvP lobby its not opponents weapons I'm checking - It's their grimoire score. For me personally that tells me all I need to know. In conclusion I agree - 95% of the time someone with high grimoire score is going to be a decent player in my opinion.