Requiring me, as the owner of a radio station, to give equal time to opposing points of view, restricts the amount of time I can be talking. The fairness doctrine would not even allow me to buy the guy his own radio station and let him use it to say whatever he wanted, I would have to give up my speaking time.
Which one of us does not understand how the fairness doctrine works, and that it really restricts speech?
and on the other hand granting you, as a radio station owner, special rights to operate over a proprietary airwave commands certain reciprocal obligations. As do all licensing agreements.
Requiring people to offer all sides in a news broadcast is important for a lot of reasons, but one of the main reasons is that a lot of people assume that if it is reported as news it is therefore true.
As a news venue it is then reasonable for you post a disclaimer expressly stating that your news isn't true, or to hold yourself to some kind of standard of veracity.
Requiring that all sides be presented is a clever way to achieve a valid goal without imposing standards for veracity. It's a self regulating mechanism.