We used to teach our children to "have a thick skin." "Sticks and stones will break my bones, but words can never hurt me." When someone took offense we told them to "grow up."
Being offended, especially on behalf of someone else, is useless. Teach people not to take offense. They'll be happier.
Words to affect people and if you don't respond to insult, you will be bullied and insulted more and more. You will not have respect and you will lose ability to influence what is going on with and around you.
In addition, men used to hold duels over words, so it was not even historical standards.
> When someone took offense we told them to "grow up."
Yes, some adults were enabling bullies like that. Especially if they themselves did not like the target. But it still was exactly that - enabling.
Just letting it go or being submissive is not functional strategy to deal with these issues.
Teach people not to take offense. They'll be happier.