That seems pretty obvious to me. There is a basic rule of social interactions that you do not unnecessarily offend, and that you apologize if you offended unintentionally. That way you don’t wind up making people angry and then they don’t want to listen to you or even be around you.
Sure, sometimes you mean to offend, but then you’ll want to do it knowingly. You’ll want to know why exactly it’s offensive to know if you want to go there. You don’t want to communicate something you didn’t intend.
There is no obligation, however, to decide that, because there are some people who are not offended by a word that it isn’t offensive to you. That’s going to always be a case-by-case situation. And, even if there is a good case that the term is not offensive, you can’t suddenly change how that word makes you feel. A decent person would, of course, still apologize for saying it and at least temporarily avoid it.
I’d also just say that, nine times out of ten, that “case by case” situation is going to wind up in the favor of the person offended, as it will be a term that has a history of being said with a bigoted meaning. So it makes sense to err on that side than the other.
There’s also just nearly always another way to say whatever it is you wanted to say. Like, when I didn’t want to refer to a piece of software that “crippled” my machine, I was able to ask and receive tons of alternatives–the one I use most is now “nerfed.” I use “moronic” instead of “retarded.” I can use the correct pronouns when referring to a trans person easily enough, too. And I can say 'transmittion" about as fast as “tranny.” I can say I was “conned” or “tricked” instead of “gypped.”
It’s not like this is anything new, anyways. It’s been a part of navigating the world since the day I was born. There are always social mores that someone doesn’t know about and then learns about.
The real question I have is why there are people who get so offended by the fact that something is offensive to someone. It’s such a ridiculous reaction. It really just seems to be about putting other people in their place.
At least with offensive terms, there’s an underlying reason why they are a problem, some harm they do.