I definitely don't think that an entire review should be based on past knowledge, but I think I would have liked to see more of it, as it does (for me) add some interesting and important points about a game. Particularly for the Mass Effect series I don't think that it would be a good idea to play it if you have not played the previous two games (in the same way that I wouldn't read the third part of a book trilogy if I hadn't read the previous two). This doesn't mean that you shouldn't be reading reviews of games that you haven't played the precursors for, but I don't think it would be wrong in the review to talk about them.
For Skyrim, where it is not as much a linear progression of games, I would definitely prefer a lighter hand in terms of what I meant by referencing past games. It should not be the whole review, but I section (a paragraph or so) could talk about past games, and I don't think this would distract me if I had not played previous games.
Your example of the Walking Dead review does do a bit more of what I don't like. Though I think you are more sensitive than I am to the amount that MitchellTF included knowledge of past Telltale games. I thought that, while the review might have made more sense to me if I had played past Telltale games (or even more adventure games in general). Mentioning something that he feels was fixed in the game that was done wrong in a previous game (and where it is decently explained: the QTE issue I thought was explained enough, if a bit clumsily, and so wasn't a problem for me to follow) is not a bad thing to do in my opinion. Even as someone who hasn't played the previous games or the game the review is about I learned that the game improved upon previous aspects by the same devs, which is good to know.
That is true, I just think that it is acceptable to give a low(er) score to a game because you personally don't enjoy it. That is why reviews are interesting to me, they are (or should be in my mind) the opinion of one person (hopefully informed about the subject matter generally so they provide an intelligent and thoughtful opinion). I think that a score shouldn't be dictated by the general popularity of a game, or its pedigree.
If we say that games are too "objective" to be judged then we shouldn't review them at all. But that is silly and we should. But because each different gamer is going to react differently to games I think that means we should embrace differences in reviews, particularly low scores of really big budget, "AAA games" and popular series. I think it is important to listen to these dissenting voices because even if they aren't the norm, they can be providing a valuable lens into the game which otherwise is overlooked in praise.