I'm glad someone else feels the same way. My angle is: these ads expect people to give up all their personal details, without revealing any of their own. I'm sure they miss out as a result. (One posting sounded almost spammy - "we're the next big social network" etc etc. No-one's gonna respond to that unless they know who you are, can check a website etc).

Edit: or maybe that's the point - if you don't know who the poster is, you're not worthy of applying.