That's an interesting but grim point. Ebola, for example, is both very deadly and very infectious, but that combination means that outbreaks tend to burn out before spreading widely. One of the early things that scared me about COVID in late 2019 was the rumors of "asymptomatic spreading" that were coming out of China.
That wasn't the only "oh shit" thing about COVID and the way things were handled early on, but it was a bad one.