Gaming critic Jim Stirling has a youtube channel dedicated to this, e.g. Air Control (https://www.youtube.com/watch?v=VYArgbWVtGc) was a famous example. Day One: Garry's incident (https://www.youtube.com/watch?v=KjTa_x3rbJE) was another trainwreck which got famous because the dev filed false DMCA claims to take down negative Youtube videos.
Both of these and many more were on steam for $30 or so
They are working in steps towards this. The last discovery update addresses a lot of the problems they had with discoverability and also focuses on rewarding better games more than subpar ones.
The reason behind showing metacritic score, user reviews, and curator reviews, along with introducing a discovery system that considers the quality of the games it suggests, and pushing some of the approval process onto the users (greenlight), has been all to try and decrease Valve's position as an authority on game quality.
There are some horrifyingly poor games on steam already, most of which get removed after a bunch of people complain about it either a) being a scam, or b) being literally unplayable, after which no refunds are given and the game is removed from the store.
But bad games, who make truthful claims, are fine, and that is intended
We have that, and it's called "installing from the developer's website".
Allowing everyone on Steam would be a mistake; driving down the minimum quality of games makes it harder to discover and reward the best games. Steam's success so far has been in quality and discounts.