given that before the advent of vaccines, communicable diseases nearly always returned, and the success of vaccines subsequently (e.g. Smallpox, Polio, Measles, etc.) it was judged 'Prudent' by the world's health organizations to not 'gamble' on an untried strategy with no clear means of being able to protect all the truly vulnerable people...for an unknown period of time....so, giving hundreds of millions of people the impression that the Great Barrington Declaration was credible would compromise the public's health and well-being...
In places like Japan, not following the Great Barrington Declaration turned out to be a very good decision...would that our country had a leader at the outset who had the same wisdom and aggressively fostered the same behavior.
btw, attached is one person's view on "Wisdom"...thought you might benefit from it.
Link: https://joshkaufman.net/practice-of-wisdom/