Also for older games, sometimes you get people playing for 1000+ hours who says that the game turned to shit 3 months ago and you'd never get that just watching a gameplay video that came out a few months after the game was released.
Steam reviews also track over time, again, videos don't. I watch videos for new games and use them with Steam reviews to see if I'd like a game or not, but for old games the reviews are much easier to get a clear picture of what the game is like the day I'm planning on buying it.
I've been gaming for more than 3 decades. Know very well what I like and what I don't. Sure, gameplay videos are great but as an old FPS guy, looking for gameplay recorded by someone who knows what they are doing takes more time. It really does. That's why I look fir videos after taking the time to read what people think.
That said, I've stayed away from professional reviews for more than 2 decades.
News to me.
Steam generally does a good job of bringing relevant issues to the top, like latest patch breaking something, less than stellar netcode on fighting games, etc.