Exactly this. Not only did it essentially wipe out entire populations and even drastically alter the course of civilizations (repeatedly), it has not "disappeared." It is still endemic in mammalian (mostly rodent+flea) populations in some areas including in the US. Every year there are people who get infected with it. I think it's an average of like 7 people per year in the US, but as usual, countries more heavily exploited by the US and its vassals get it worse. Hundreds of cases per year in DRC for example. It's hasn't "disappeared," this antivaxxer nitwit just doesn't know about it because modern medicine has made it treatable and precluded its ability to spread as it did in previous centuries.