As a reminder: during a pandemic, before there is a vaccine, the goal is to lower the rate of infection, spreading the epidemic out over time so that the hospitals are not overwhelmed with the sick.
It won’t necessarily lower the number of infections, but it will lower the number of people who die (because the healthcare system is not overwhelmed).
This is why early counter measures are important in an epidemic. Their intention is to lower the rate of infection so that the epidemic is spread out over time and the peak demand for the health care system is lower.
While the total number who get infected might not change, the containment measures intend to avoid an outbreak trajectory in which a large number of people get sick at the same time. This is what the visualization shows.
This is the reason that limiting the magnitude of peak incidence of an outbreak is important – health systems can care for more patients when the number of cases is spread out over a long period and it is not peaking in a very short period.
A worst-case scenario for a pandemic of COVID-19 is that the number of patients at one point in time is so large that health systems would fail to provide the required care for some of them.