Pass it on
If one person says two plus two equals four and another says it equals seventeen, the journalistic obligation is not to report that "opinions differ on basic arithmetic" and let the audience decide.
This is exactly what the both-sides doctrine demands: that every claim be granted an equally-weighted counterclaim, regardless of the distribution of evidence, because balance; defined as equal time, not proportional accuracy; is the highest journalistic virtue. The problem is not that both sides should not be heard. The problem is that not all sides occupy the same epistemological elevation. Some claims are standing on a mountain of data. Others are standing on a tweet their cousin sent them. Treating both as though they deserve equal consideration is not fairness. It is a category error wearing a press pass.
The math of this is instructive. If ninety-seven percent of relevant experts agree on a conclusion and three percent disagree, giving both positions equal time is not balanced coverage. It is misrepresentation; specifically, a 4850% overrepresentation of the minority position. Imagine a weather forecast that gave equal time to the meteorologist who predicted sunshine and the caller who predicted locusts. The format would not make you better informed about the weather. It would make you worse informed; and it would do so while insisting it was being "fair."
Proportional accuracy is not a threat to fairness. It is the only kind of fairness that corresponds to reality. Equal time for unequal evidence is not balance. It is fabrication.
The antidote to both-sides-ism is not to silence dissent. It is to report dissent honestly; with its actual weight, its actual evidence base, its actual standing in the relevant expert community. If the dissent is fringe, report it as fringe. If it is unfounded, report it as unfounded. The audience deserves to know not just what the claims are, but how seriously to take them. And determining how seriously to take a claim; weighing evidence, assessing expertise, distinguishing signal from noise; is precisely what journalism was supposed to do. The both-sides doctrine did not make journalism more fair. It made it less useful.