Knowing your ABCs is essential to academic success, but having a last name starting with A, B or C might also help make the grade.
As graders go on grading, their comments become more frustrated and their good-will becomes much sloppier. At least that's the hypothesis to explain this. Researchers found the reverse effect on graders who sorted in reverse-alphabetical order.
I think blind marking is important. I have literally heard people objecting to proposed grades with phrases like "but he's a bad student" or "but she's really bright."
I can't imagine how, unless you only had 20 of them or something?
Back when I was a TA, I had an average of 120 students per semester and we didn't necessarily grade our own students' work (it was usually divided by topic).
So if I'm grading 120 assignments - or worse, 480 pieces of exam assessment- and only 25% of them are from students I regularly interact with, I don't think my subconscious has any idea 99% of the time.
Even with smaller classes... you're just seeing too many people with similar thoughts and styles over the course of a year for any of it to imprint on your mind that deeply. Occasionally it's going to be obvious, but I still think removing a level of bias through anonymizing is best practice.