Nextstrain has a nice graphical overview of virus pathways. It might well be that containment failed, and that a single person caused hundreds or thousands of

Nextstrain has a nice graphical overview of virus pathways. It might well be that containment failed, and that a single person caused hundreds or thousands of the deaths in Italy, much like patient 31 in South Korea. On the other hand, without those extra deaths, authorities would simply have waited a bit longer with a lockdown, people would have acted as usual for longer, and the end result might just have been very similar with a delay of a few weeks.