This is exactly your point. If you believe they are only curating the garbage, good luck lol.
Because, then again, it's easy to claim "easy curation is to prevent this game from happening here". Although it's more difficult to claim where it does extend. Take this game for exemple:
http://store.steampowered.com/app/597220/West_of_Loathing/
It looks like garbage. If I was curating, I would've refused it. Although, looking at reviews now...
http://www.metacritic.com/game/pc/west-of-loathing
Yup. It seems to be actually a great game.
From the header, to the screenshots, it looked like a shitty shovelware game with no place here. You can bet if it was curated, this would've never released here.
And you know what ? I'm betting that everyone in this thread would've claimed the same before getting actual opinions on the game.