The potential nominees are submitted by the producera of the show btwThat's why I can't stand the Emmys. You could fill the whole acting category with talented people from OITNB, but emmy voters watched a couple episodes of season 1 and thought "okay Uzo Aduba is the person we're going to nominate from this show" and that's just the way it will be until the show ends. It's like that with everything, it takes a miracle to cause a shake up.
I don't think most of the people who vote even watch the shows tbh