> your advice based on new evidence is
Because based on that old evidence that seemed so sure at a certain moment in time the lives of hundreds of millions of people were negatively affected (lockdowns, job losses etc), so one could forgive a part of those people for not giving a damn about the evidence subsequently changing and we being closer to the truth, in a scientific way.
Almost no-one cares about science, even the majority of people who materially support science by giving scientists money don't care about science (most of them have ulterior motives, like the ability to militarily be superior relative to their foes based on said science, or the ability to gain even more money compared to what they put in etc), long story short almost nobody really cares about science in the way that (some) scientists do, i.e. getting us closer to the "truth" (whatever that "truth" is).
In that respect, telling those hundreds of millions of people something like "but, you see, we were doing science when we were negatively affecting your lives based on evidence that proved out to be further to the truth compared to the evidence that we have now" means, in the best case scenario, that you're taunting them, in the worst case, that you're taking those millions of people for utter fools that should just sit like ducks in the way of science.