Even though many (or even most) people probably aren't offended by terms like blacklist or master/slave, there's a non-zero number of people who are. Obviously changing terminology isn't going to end racism, but it will have a small positive impact on some people. Even if 99% of people don't care, they're not harmed as long as the new terminology is clear. IMO there's no semantic loss by going from "master/slave" to "primary/replica" or similar.