“The GOAL is HERD IMMUNITY — just like regular flu and the common cold.“
What is the evidence for the existence of what you are calling “herd immunity” for any human coronavirus?
Example of Herd Immunity.... Various flu seasons have higher impact to younger folks vice older folks who had already developed natural immunity because of getting similar flu years ago — when they were young.
From a random selection of web pages via search
https://www.ecdc.europa.eu/en/seasonal-influenza/prevention-and-control/vaccines/immunity