Are you saying that we shouldn't vaccinate, because strict lockdowns worked, against the COVID-19 original strain, for a while?

It's technically true that this worked then, but 2020 is gone, not to return. a) new COVID strains were inevitable and b) prolonged strict lockdowns unpalatable and c) mass vaccination has a huge benefit. As part of a multi-pronged strategy, of course. Depending on only one measure, be it lockdown or vaccination, is not going to work.