Right, that's been my thought too. Reporters etc. currently seem to be talking about 'herd immunity' as 'enough people immune that outbreaks can eventually peter out, without flaring into epidemics', but I always understood it as 'so many people are immune that the few who could catch it are protected by the enormous herd of immune and therefore non-transmitting people around them, who act as a buffer to the rare active case'.

And as you say, we've never achieved that, for anything, without vaccines.

On the other hand, we could wipe Covid out the old-fashioned way. We have a good enough handle on how it's transmitted now that we could use precautions consistently in public, test all travelers (including truckdrivers, politicians, and 'driving to the next town over for errands or visits'), quarantine everyone who tests positive until they are definitely not contagious any more. We could wipe this thing out in three or four months if we were determined.