You mention a "factual reality" in an area of disagreement but there is no such thing prior to the establishment of a consensus. The phrase "undermine everyone's belief in the factual reality" is misleading because it assumes that there is already some established consensus that is being undermined prior to its own establishment. But of course, one of the ways to establish a consensus is to talk about it as if it were already established and legitimate

> So talking about what the public believes, independent of any proposed course of action, ends up being quite relevant.

I think that talking about consensus can be useful, but I've yet to find an example of anyone discussing what the public "believes" in complete disinterest and without some implicit course of action