I'm not convinced that hybrids are inherently better than Shinigami.
If that were the case, what would be Kubo's point in seemingly saving some of the Shinigami for later fights?
We've yet to see Unohana fight at all; Ukitake, Yoruichi, Urahara, Tessai, Isshin, Gin, and Aizen have never really been in fights that they were able to finish (in other words, take seriously).
I think it's more likely that potential varies from person to person, and you can't judge a person's potential by what race they are.
Besides that, being hybrids would make the nakama irrelevant. I don't think Kubo would do that to Rukia.
So what are your thoughts on this?