Blacklist is a word that stands out, an interesting combination like other English words or phrases and I had no issues with learning it. It's also a word with a rich history that doesn't seem to have had a racist origin. And because it was used since 17th century and is still in use, non-native English speakers have to learn it anyway.
"Master" was more legitimate as a target for change, but again, I don't think anyone had issues with understanding it. This is like when mother-father or male-female is used to describe electrical connectors.
And also, the bigger problem with changing "master" to "main" is that "master" was a standard and the change was painful. At work our branch is still called "master", any change won't happen soon, as people have better things to do (needing to reconfigure CI, plus red tape due to policies and ACL policies) . So now people have to be aware that the default can be both "master" and "main", increasing the knowledge one has to possess for no good reason. It's not like the change from "master" increased the quality of life for anyone.
Note that I have no issues with changes that are made for clarification. For example, in database replication, maybe it's better to talk of a primary database and of replicas, which seems more descriptive and aids learning. But I don't think many such changes were motivated primarily by the need to clarify, but by the need to sanitize the language and I disagree with such a motivation.