Because I've found that the companies that are offering the type of compensation I'm looking for are willing to discuss it. They know what the type of talent they're looking to attract makes, and that they aren't going to be interested in wasting their time.

Might there be some out there that would be willing to pay me what I'm looking for, but unwilling to discuss it up front? Possibly. But after wasting several dozen hours of my life with offers that weren't even in the same ballpark of what I was making or what I was after, I made the decision to not bother if the recruiter wouldn't be candid up front.