1) The corporatization of social media is a big factor. There's big money involved in controlling reviews. Critics and influencers devoted to certain fandoms inevitably get influenced, pressured, infiltrated by studios who expect favorable treatment towards their product or that entity loses access, gets attacked, etc. Try being a blogger who writes about something like Star Trek for example and consistently writing bad reviews. I'm sure you're going to lose any studio access for interviews and all kinds of good things if your criticism ever becomes a little too harsh.
2) Everything has become political, and the media class is totally out of touch from what average working people are looking for. A critic is going to want to rate some drama about a queer latinx non-binary vegan sex worker thats trying to come to grips with his atheism while interracial dating higher than the story deserves just to appear to have the "correct politics". Typical working people don't care as much about that, and just want to know if something is entertaining and worth their time and money.