If I may generalize this away from game reviews, or indeed reviews of anything, the amount an opinion matters is really up to you. Of course each and every person is entitled to have an opinion amount thing X - even those who have no experience with it whatsoever. It is up to you, however, to weight those opinions accordingly.
If someone leaves a comment on a video that simply says "this sucks" (a word with which I have a whole host of problems with for a description of opinion) without elaboration, then I am going to almost immediately dismiss it. If instead the comment says "this sucks because of A, B, and C" I am going to value it more heavily. I may not agree, but I will at least understand why the thing is disliked, and where that individual is coming from, and it will factor more into my personal feelings towards the video.
Unfortunately, it seems to be the prevailing view, in the general public at least, that ALL opinions are equally valuable on all matters. This is where the issues start to crop up. Suppose the government is looking to further develop technology Y, and wants feedback on whether to pursue it or not. If I am a scholar with years of experience with Y and am well versed in its development, possible benefits, and downsides, my opinion should be weighted much more heavily than that of the average person who may only known about Y from news reports. This is not the case.
Of course, this idea can be furthered to the idea that people are then not all equal, which is wrong. We are all fundamentally equals. We do not, however, have a hive-mind of shared knowledge and experience from which to base our decisions. As such, the people with the most understanding should have a more significant say in that area.