It's rare that "deadwood" and "quiet quitters" do literally zero work. Even if you feel that your job is secure, you might not appreciate having their work dumped into your lap, especially since there's a good chance that it's not critical-path work. And you might not want to be in an environment where morale is low and trust in leadership just took a major hit.
They're deadwood if they cost more than the value they produce. Nobody missed them. And the livewood didn't have to go redo all the stuff they messed up.
