Of course there are downsides, there are lots. The first downside is that it creates work. Yes, some tools will break, it's always going to happen when stable

Of course there are downsides, there are lots. The first downside is that it creates work. Yes, some tools will break, it's always going to happen when stable identifiers are renamed. No, saying "it was always theoretically possible" is not a get-out clause. Breaking software has a cost, often a large and unpredictable one. Any protocol, any API can theoretically change at any moment, which is why successful software companies often promise not to do that. Secondly and more subtly it creates work discussing it, actually doing the renames. This is time that would be spent on other useful things, but instead gets sucked up by this. Thirdly, the premise is offensive and wrong, which will anger a lot of people. The implied belief behind these changes is that the people who chose to use the word "master" before were racist. And now all this fuss has occurred, there's an even stronger implication that anyone who does not rename their branches is racist. But this isn't true and thus a deeply offensive case of false accusations on a truly epic scale. Moreover this appears to assume that language creates reality, so strongly that renaming "master" to something else will actually alter people's deeply held and embedded beliefs based on their own lifetime of experience. There's a lot of evidence this idea is completely false, in fact linguists haven't believed this for nearly 100 years. So it's anti-scientific. Fourthly, everyone knows that exactly because the premises are aggressive and irrational, it doesn't stop with this. The sort of people demanding these changes are insatiable. Once you start paying the Danegeld, you never get rid of the Dane. Next up, anywhere that uses whitelist and blacklist. You think renaming master generates an acceptable level of breakage? Wait until those two start getting renamed and a whole lot of security mechanisms stop working. What about whitespace? No, the madness (for that's what it is) will never end. The downsides to giving in to this kind of aggressive, toxic demand are limitless because there will never be a point at which the Woke Police will feel they've done enough - they will continue demanding that when they yell and get upset you dance for them, forever, until they are expelled from the communities they are attempting to take over.