>>What would have been the alternative? Is preparedness for the worst case scenario worthless?

Proven science for pandemic threat involved closed borders and quarantine. Whereas some are saying that shutting down all of society seems more of an experiment by politicians who remained committed to open borders until too late, then panicked.

But where to close borders? There's no precedent for New Jersey to barricade your NY border so once it was loose in NY you were always going to see it too, especially if there were 2 weeks of incubation and interchange before the very sick minority began to present. Unless there's international co-operation and information sharing so NY can keep it out, you're in the firing line too.