I think this kind of view of game designers is common around GameDev.net. At least, that's what I noticed.
But do *something*.
Not just "I have a grate ideea 4 a game! Make it 4 me!"
Are all game designers really like this?
Only the amusingly bad ones.
For recruiting for the sorts of projects that are suited for GDNet in today's day and age, I'd expect the designer/leader to have a playable prototype. It doesn't have to be pretty and it doesn't have to be complete, but IMO there is no good reason for someone not to have something playable to sell their idea to prospective team members. There are a ton of cheap or free tools out there these days (GameMaker, Unity etc.) that let you whip up something quickly with little to no programming experience. If a designer can't throw together a prototype then that suggests that either a) they don't really know what their game is about; b] the game is way beyond their scope and/or c) they're too lazy to put in the work.
Edit: This doesn't count projects where the explicit purpose is learning, i.e. "I'm a newb and want to learn how to make games, are there any other newbs who want to join in?".
Off-topic: How do you stop the system turning b with a bracket into a smiley? Silly automated smiley system...