The original choice of the word "master" in the technical context was referring to that of the absolute master driving the disposable slave.
The article (or at least the research behind it - it’s been a little while) had two main points.
1. The usage of `master` in Git did not derive from BitKeeper, but was chosen by Petr Baudis.
2. The intention when choosing it was for a “master recording”, not related to the “master and slave” meaning of the word.
I’ll also note that BitKeeper’s usage of the term was not related to slavery either.
I understand that there have been many usages of “master and slave” in technology, and understand the efforts to remove those usages. You seem to be drawing a link between those usages and the usage of the word `master` in Git. I believe no such link has been demonstrated, there is good evidence that they are not linked, and the modern usage is not related to slavery at all.
It’s possible that the historical “master and slave” usage has tarnished all uses of the word ‘master’ in technology for all time. If so, so be it, but this is a very different argument to the one you seem to be making – that having a master branch is “carrying forward 18th and 19th century misguided beliefs” – and there are far better (and more correct!) arguments than these if you want to change the name.