If you can't tell me anything about what company I'd be working for, I can't tell you if I'm genuinely interested. I'm not a faceless program that responds automatically to the right salary, equity, and title inputs. It's a bit more complex than that. At the very least, I need to know what company and what product I'm going to be working with. (And no, "it's a ___ app" is not sufficient. Show me the actual product).
Some recruiters are awesome, btw. My general experience is that in-house recruiters are better than hired guns. The in-house people know the company and its culture, and they often have direct lines into the hiring manager. Not all of them are great, of course, but there's a better wheat/chaff ratio there.
[1] I realize there's often a political need for secrecy, such as when you're replacing someone currently in a role. Or if you're trying to poach from a competitor for a given role, and you don't want it known that you're doing so. That said, both of these scenarios will out themselves eventually. In my experience, any veneer of confidentiality will evaporate the second you approach your first serious candidate. Especially if you're talking to candidates at a competitor.