Supposedly they handle all of that as well, but the tradeoff didn't make sense in my case.

The other key difference from the entertainment industry is that in-demand artists can potentially derive a large percentage of their income from royalties and "image rights", so it's a good thing for them to retain an agent who's incentivised to find that unpaid TV slot in New York that'll help them "break America" but advise of the pitfalls of an apparently lucrative advertising gig they've been offered. Agents for successful entertainers, in other words, are supposed to boost a wide variety of income streams related to entertainer's image, including pre-existing ones.

Contract programmers on the other hand, generally receive their compensation for a project in cold, hard cash, without any lucrative sidelines in selling T-shirts with pictures of their face to manage, or concerns over whether taking on a project for Yahoo will dilute their brand equity or boost their autobiography sales. It's difficult to see where 10X adds the value in cases where they're not finding the work. Interview coaching and advice on upping your rate is not hard to find; any recruiter that does have a position will offer it without wanting a piece of your existing income.