I agree that there is a lot of weight given to a reviewers words and they control certain aspects of the gaming industry that they maybe shouldnt, but again it just comes back to customer preferences in how you perceive the medium. I like using Let's plays as my source of information, but mostly for 4x and RTS games with some exceptions, as to me a Let's play shows everything you need to know in those games, but otherwise I feel like you are missing out on two things in other genres.
-The feel of the game and the draw of the characters you play, which is compounded if you enjoy listening to soundtracks like I do, to me they are the biggest immersion factor at times (again one of the reasons I do prefer Witcher to Fallout, but thats just personal preference (and again it speaks volumes about the Witcher to say its OST is better when Fallouts is fantastic itself).
-The feel of the first few moments to me are ruined if you play let's plays. One of my favourite games companies is Naughty Dog and I will never watch a Let's play of their games cause it WILL ruin that incredible cinematic story telling. Can you imagine the emotional attachment to Last of Us being as strong had you just watched the intro instead of playing it yourself?
To me Fallout is better played for the first time, and better understood in written format than it is viewed on youtube. If watched Fallout tends to look boring, if played you get a completely different vibe.