To be fair, the herd immunity idea was floated around quite early in beginning of the pandemic. But it was quickly thrown out when governments saw the infection rates and deaths spike up. Ever since, vaccination has been the dominant (hammer) solution for the virus. (Vaccination) Has been the background track for this pandemic and still is to date. Natural immunity is only coming back because Omicron is not as deadly as the previous strains. It was never an option before.