Comment by SpicyLemonZest

This is one of those things that's hard to understand without practical moderation experience. The presence of an insulting meme creates the idiots who spam it, and creates a larger category of people who deploy it to toxify what would otherwise be polite and respectful discussion. And low quality comments that get a couple laugh reacts, even if you can consistently remove them within the hour, are fully capable of propagating it.

Keyword bans are definitely a heavy-handed option, they do risk the Streisand effect, and in the worst case that can require the scorched-earth counterresponse described in the source article. But sometimes there's just no other way to kill the meme.