Well, sometimes "some people" earned few put-downs.

With all due respect to your mother's well intentioned advice: "If you don't have something nice to say, don't say anything" in my experience, while superficially a laudable sentiment, is in practice mostly used to keep people quiet and conformant when they should speak up and call a spade a spade. It supports the "keep things outwardly and superficially nice but inwardly seething" ethos of the American midwest and much of the South. I think it's important not to be back-stabbing and gossiping, of course, but there's nothing wrong with calling out actual bullshit, either.

I fix my sense of outrage at stupid remarks by being snarky!

It is a sign of their insecurities. I don’t feel sorry for them but I wish they could find another way to address their pent up aggression, sometimes the mildest of remarks can trigger a completely uncalled for invective.

Being compassionate towards others is always the wise thing to do.