I'm right there with you Yahtzee; green open fields can also make a great place for a garbage dump.
Y'know, if they had made only the Concept section the only part of Greenlight that's open to anyone, and you had to go through Valve's and audiences' approval to upgrade into the game section, I think there would be a lot less garbage in Greenlight in general. I mean, yeah, call it unfair to treat a complete (or "complete") game like a concept, but if such a two-stage approach is used it would deter several people who just have an idea or some poorly-made alpha or beta build they're trying to push as a game.
And you can't just be an "idea guy" either. If you want to make games, you need to at least learn one of the many skills a development team needs. Writing, coding, art assets, music composition, sound effect creation and foley, even skills like accounting and management are necessary.