Suppose someone writes a story that attracts regular readers and it contains a certain element that he/she like in particular but most of everyone else doesn't like it.
That's pretty much the important part. Long story short:
it's your story, not theirs. Sure you can listen to the reviews, but not all reviews are criticism, nor all reviews are complaints, and those (few) that are criticism are not always constructive, useful or even correct. You should pay more attention to commentary that is... closer, if you have provided the adequate channels.
So basically to the question of when is the author.... any of the above? I'd say the key answer is when they refuse to
consider changes (note the choice of word) to the story because a review says they have to go differently. Remember, it is your story - but it does not also have to be your
mistake, and being open to changes helps a lot with that. Also remember that statements of the kind of "you did this wrong, you should have done that instead" is a proposition, not a fact - the accusser still bears the burden of proof, and it might turn out that even if he is right, a solution other than his can be applied.
Also I'd say
building a relationship with your stable reviewers helps remove a lot of the unfounded feeling and other issues that stem from such reviews and comments. If you're going to listen to someone who is telling you that you are portraying a sequence of events in the wrong way or that you should die because of writing about Subject X that is banned by his religion, his One Party or the retarded-Youtube-commenter personality facet buried in his brain, then in the least it should be someone who knows your style of writing well enough that you can trust their opinions to be, for lack of a better word, relevant.