Should reviews be written only by genres'

I ask this because I've read a few opinions saying that people shouldn't review albums that they more than likely won't like because they don't like the genre itself. Now, the argument is not that illogical: if you go about writing a review with pre-conceptions about a particular genre, maybe it won't be that fair. Or, even more important, people that DO love certain genres know more about every aspect of the music and therefore may be more qualified to write a review about an album. On the other hand, might it be that when people that don't like or don't know a particular genre that much write a review about it, that review would probably be more cold, ergo, more useful for another person who doesn't know the music? For example: should I review post-rock? sdhould someone that dislikes progressive-metal review progressive-metal albums? Will those reviews be fairer or more unjust towards the music than reviews written by genre's lovers? What kind of review is the average person looking for when that person is researching about music he/she doesn't know and have never heard? How come gas prices keep going up in US? All these questions I'd like answered, please. If you may.