User blog comment:Xilinoc/Ch. 542 - THE BLADE IS ME/@comment-10699642-20130619212112/@comment-10699642-20130619220228

I would also doubt that its important if you are a pure blood or a mixed blood (like Ichigo only being a half blood Shinigami but still far stronger than the most Shinigamis) but sometimes people think that way. And Isshin already gave us a hint. He said that half Quincys had trouble with using Blut while pure blood Quincy used it almost automatically. So maybe yes pure blood Quincy where better at the start but I would guess that with training they could catch up with a pure blood. So thats maybe why a pure blood Quincy would be recognized as superior.