Those influencers are for sale but they're still more reputable than the traditional media. For the most part they're not very good at faking enthusiasm for a bad game because they betray more genuine emotion in the video format they use, vs text-based mediums where it's trivial to lie with a straight face.
No they aren't more reputable, they're cheaper and unfortunately have greater impact. A streamer playing a game to their 10k audience, despite the game being shit, will still result in guaranteed sales in a way that makes full blown marketing campaigns in traditional media pale in comparison.
It literally doesn't matter how good or bad they are at acting, all that matters is the game gets coverage on their channel, that's exactly what the campaigns are paying them thousands for. Yes, thousands.
Reputable was the wrong word; the point is it's easier to tell when they're lying because their face is on camera. Written reviews don't have that.
I can tell if a game is good or not by watching people play it. I haven't been duped yet. It's always obvious when the game is a stinker and the person playing it is straining to look like they're having fun.