> Once "master" is used in combination with "slave", it refers back to slavery and leans on it, there is no doubt about it.
This is not how language works. E.g. if you recall the debate about this, some people dug up an email from, I guess, Linus that mentioned master and slave repositories and some reasoning around that repositories are identical to branches yadda-yadda. (Or maybe the email was actually referring to the terminology used in another DVCS they were taking idea from.)
So they have proven that say some 15 years ago the thing was originally named so because of the master/slave concept (the technical concept). However, nothing proves better than the need to dig this up that meanings indeed do change. Especially when you use a name that has multiple meanings, like master. They named it master because of master/slave but the majority probably never knew this (I've never heard anyone talking about a slave branch) so just assumed master is master as in master copy, source of truth, etc.
This is how language works. After all, this is how the word master acquired the meaning of "owner of slaves" which it did not have originally. So yes, it was named master because it was related to the concept that we (used to?) describe with the expression that does refer to slavery but we definitely changed the context over time.
Regarding the name change, you can see several ways how it does harm. One of them was described in the post: by diverting the discourse and using up the effort that could have been spent on handling the real issues. Whether we are talking about people who did want to do something positive and now they feel they did (this is what the post is about) as well as the people who could have been recruited for taking meaningful actions but got pissed off/tired of this stupidity.
I honestly think that both this master branch thing and black/whitelist was 100% stupid because, as said in the blog post context . I'm not sure about the master/slave, but I'm 100% willing to accept that it can be offensive (and I'm treating it as such), though it would be interesting to hear the opinion of those affected, like the post author. (I just miss the nuisances here as I'm not from the US. Before hearing all the debate around this, I would have simply said that slavery was a wide-spread phenomenon during human history and it refers to that concept. That doesn't mean we don't think it's a terrible thing to do to a human being or that we don't empathise will all of those who had to endure it during their life.)