We didn't. Some did, but not all of us.
I wonder if it happened for anything other than master/slave, whitelist/blacklist? Nothing else seems to come to mind.
Imagine if people said airplanes need to stop saying retard because that's offensive! For the record, it means to pull the engines back down to idle before touchdown.
Master is good example. It is not offensive word in either of the cultures I grew up in, and its strongest associations for me are “male teacher” and “highly skilled craftsman”. Blacklist sounds related to terms like blackballed.
The history if the US makes terms that even sound as though they are related to race or slavery a lot more sensitive.
But on the other hand, main is shorter than master, and allowlist is self explanatory unlike whitelist, so personally I'm fine with these changes.
I also dislike American concerns getting special treatment and it comes with the background of the adoption of American English, which often loses meanings and distinctions.
Edit: I always assumed there was a technical reason for why IDE hard drives use "master" and "slave"; IE, if the master used older versions of the IDE protocol it could slow down the slave, or that the master had some priority on the bus. Specifically, if "1" and "2" or "primary" and "secondary" were designations instead, it might omit some kind of detail that was important to whoever picked those names.
Keep in mind that language shifts really only work when (almost) everybody goes along with it. When the PC police try to change the language in a top-down manner (and then imply that those who don't agree are bigots), it tends to backfire.
Absolutely. I never cared about my default branch name, but once the PC people came, I made sure to never call it "main".