True, although as stated this person isn't reviewing the game. It's just a video showing off the game. And most 'skilled' gamers can tell that the player isn't quite controlling it well.
Most of the reviewers, even at Polygon, play games for a living. Their skill level is only something to take into account, but it doesn't mean that someone can't review a game simply because they aren't as good as what is considered 'skilled.'
We have a wide variety of reviewers from many different outlets. It's good to have a variety of perspective. Many people who play games aren't quite as hardcore about the hobby as we are. This is just a perspective, and I think it's better to consider these points instead of shitting on it after watching a 10 second clip.
I don't think your overall point is wrong. As I said, I think having different perspectives is cool. Edit: Like the poster just below me points out, getting Conan O'Brian's opinion on games is hilarious to me, because I understand his position and that he doesn't play games at all outside of those 'review' segments.
However, I also think playing a game this poorly has an effect on how much weight I can but on that reviewer/commentator's opinion (I realize that in this specific case the person isn't reviewing the game, but generally speaking) in their final analysis/review/opinion on the game. This video isn't really framed as "hey we had my friend who never plays games give DOOM a shot for an hour!", it represents Polygon when it's posted.
By no means am I saying every reviewer has to be able to beat Ninja Gaiden Black on the highest difficulty to review games, but honestly in this video I just see a weird lack of ability to control the game at all, which is a bad look for a large/professional website. It's just kind of eyebrow raising.
As a comparison, I would also raise an eyebrow to a book reviewer who couldn't understand the basic themes in, oh, Heart of Darkness. Sure, there are a lot of readers that may not understand a lot of novels beyond the very literal level, either. but that's not what I'm going to a professional critic for - I can get that at looking at Amazon's reviews or, in terms of games, a random comment on a game's page on Steam.
It's just not a good look if you ask me. A website that frames itself the way Polygon does kind of needs to convey to the reader (me) that their opinions are coming from an informed or capable place, and gameplay like this makes me sit back and question that.