> At what point can we stop encouraging that?
At no point. That's how science works. Those who are opposed will bring up the best arguments available, even if those arguments aren't new. They'll get evaluated, rebuffed, accepted, etc. That's how it's supposed to work.
Many of the ideas you currently believe in were at some point rejected and ignored, frequently for decades and sometimes centuries. Bringing stuff up again, over and over, is a good thing.
If you are so thoroughly convinced that you are right, that is the surest evidence that you're doing it wrong. Always allow for the possibility that whatever you believe may be off and can be improved, even by ideas that aren't new.