which is a rather different thing
I concede that on the face of it, it looks like a different thing. But I would like to suggest that when it falls to a single organ, the government, to decide what is and is not 'controversial' as well as what is and is not an 'opposing' viewpoint, it's not different at all. Imagine the FCC declaring abortion a 'controversial' issue (it is) and that the 'opposing' viewpoints consist entirely of whether a fetus should or should not be aborted as late as the third trimester. It's an abuse of power that was directly foreseen by the founding fathers and guarded against.
Opposing viewpoints on issues are already widely and freely available, just not necessarily in the exact same news sources (though they often are).
Which is why any pushing of the 'Fairness Doctrine' looks to me like nothing more than an attempt to squash opposing viewpoints while striving to give the opposite impression to the gullible.