I’ll note that avoiding Master/Slave doesn’t require changing the letters of the acronym; At work we’re switching over to using Microcontroller Out Sensor In / Microcontroller In Sensor Out
As for why: Because I really don’t care what sequence of letters is on my schematic as long as I can understand what it’s communicating, and if that is a little thing I can adapt to that will make someone feel more welcome and comfortable in my community, WHY THE HELL NOT.
As a card carrying member of The Majority™ in this and most contexts, it’s easy to dismiss or not even consider things that would give others pause, which means the environment that grows up organically around me and others like me is a reflection of our concerns.
Imagine an EE community made up of exclusively of former slaves and their descendants. They almost certainly wouldn’t use Master/Slave as part of their technical lexicon because they would make the conscious choice to use something else, and this one small “inconsequential” change would combine with others to create an environment different from ones grown around people of a different background.
Now imagine an prospective EE that comes to a crossroads and sees both groups; one that has changed something that they don’t like, and another that didn’t care to think about it or decided it didn’t matter. Maybe this EE prospect wouldn’t notice the difference and would choose a community based on some other criteria. But maybe they do notice, either because they come from a people who were enslaved, or for some other reason.
Consciously or unconsciously one group will almost certainly be more welcoming to them than the other. I know one of these communities exists, and I’m doubtful about the existence of the other which means there are a whole class of people that will not feel as welcome as they could in our community and why? Because we couldn’t be bothered to change something that we didn’t care about until now?
I know there are certainly some now that are saying to themselves “well if something so small would keep them out of engineering, clearly they probably shouldn’t be one anyways” or some other gate-keeper-ey bull, to this I say: you literally have no idea what such a person is capable of so maybe wait until the data is in before making a decision. You know, like an engineer.