It is a highly acclaimed game, both by millions of fans and game magazines/websites. It is one of the few AAA games with exceptionally high average scores, again from both journalism channels and gamers. Considering that lately there is hype because of the imminent release of the second expansion, I would think that many people are now playing the game and the first expansion again (or some, the first time). Those should be the ones adding the reviews there.
About the conspiracy theory part... Firstly, even if they did, do you really expect them to say that here in the forums out in the open? And secondly, in the last decade that I have been following CDPR (since the first game) I never for a second thought of them as a company that'd do that. Their customer first policies and even their game distribution platform and how it works (DRM-free and so on) are kinda testaments to their trustworthiness, I'd say. Anyway, I really don't know what you expect to get to here, but these are my two cents.
Edit: Oh, lastly, before I forget: Does anyone actually care about the user reviews on Metacritic? They are mostly either incredibly high, or incredibly low ("I don't like this game! 0/10!"). Watching streams or reading Steam reviews sound like much better options. MC user reviews sections are (apart from the average score they report and its comparison with other games in the same genre/release window, I guess) mostly garbage I'd say.