I can't answer for all leaders but I can only give my opinion. I will not allow a high streaker into my clan. Once again that is only my opinion and for my clan. Each leader has their own set of standards and perhaps streaks are not one of them. If the player created the streak by power leveling then that is the same thing as cheating in my book. It allows the player to level up faster hence giving him/her access to the higher ranks weapons that he/she would normally not have access to.