I think the title needs to be changed to reflect the gist of the post: that for _startups_, recruiters are probably a waste of time. For a more established organizations, recruiters tend to work, I think.
Or at least they do in my idealized fantasy world, where the role of HR is to acquire, foster, encourage, and compensate talent.
It's particularly useful to use recruiters to find freelancers (mileage varies a lot of course).