[aisengard]

I always thought it was because the recruiter only cares about whether you accept the offer, not really how much the offer is, and so will either negotiate based on that, or else pressure you to accept whatever offer they can muster. Plus, if the recruiter can bring in people who accept lower offers they're more likely to be used by the employer. Hence, if you accept an offer through a recruiter, it's likely that you're accepting a stunted offer.