Herd Immunity

In 2019, there was a massive outbreak of the measles in New York City for that reason.

In 2014, a measles outbreak in Disneyland sent the number of cases to a 20-year high. Without herd immunity, where enough people have had the disease to avoid driving major outbreaks, future spikes will likely be much bigger.

Furthermore, limiting isolation to only high-risk individuals and cases would be much more practical and likely to work since the more people need to be quarantined, the less effective is the quarantine. It would also still relieve much of the stress on the medical system since most of the severe outcomes occur in the elderly, according to the Centers for Disease Control.