We could say the same thing for the farming. Some people hunt 50h and they get 2 rare forms, some players farm for 200h and they don't even get one. That's how RNG works, i'm not in favor for a pity system. The only thing that is sure is that you should keep farming chests and it will pay at some point
For me it's a - 1 but thank you for the suggestion
Good luck to you and have fun