By assuming that different games have both an equal volume (and weighting) of detractors, you simplify what is actually a very complex equation.
If folks really want to drag this down the well of professional journalism vs. user reviews, you first have to understand the evolution of games journalism and its relevance to review scores, in addition to how various user rating systems work and their historical (and varied) exploits. Even unrelated examples like
Boaty McBoatface are a handy reference here (and that's a completely apolitical example that I chose precisely on purpose to that end). As a general frame of reference, an overwhelming amount of user reviews are based in an emotional response (see the recent reviews of Civ 6 relating to the Gold Edition not having an upgrade path for base game owners - this is completely irrelevant to anyone looking to buy the game, it's based purely on personal anger at people who even in some cases say they enjoy the game! Hardly representative of the game's quality in that case). Professional reviews, while reflective of the writer's own likes and dislikes to an extent, are typically far more balanced because it being a profession, the people involved tend to have to balance their analysis better.
It's like professional anything vs. hobbyist anything. Certain hobbyists can indeed be excellent, but on the whole will reflect a completely different process to professional equivalents. Much like how there are very few modding teams that are run like a professional software development team (and how personal issues often break teams up, whereas in the professional world if you want to keep your job you often don't have a choice regardless of who you like or not), the metrics involved are completely different.
Like I said earlier in the thread, this isn't to say user reviews aren't useful. Emotional feedback is
incredibly important when making games. It just so happens that so is a more balanced (and often technical) appraisal depending on what you're looking for in a game recommendation. Some folks don't care about technical aspects. Others do. I know if I want technical details about a game, Steam's user reviews are
not where I look to go for it.
Notably, if I were wanting CiV multiplayer, then the professional reviews of the time wouldn't have prepared me for that either. However, similarly, if I didn't care about MP, then all of those negative reviews and their impact on the overall Steam rating of the game (however visible it was back in Steam's relative infancy) is completely useless for me, and obscures what I actually get out of the game.