The theory is that if the recruiter has a high level of control over both candidate and client, the odds of a positive outcome for the recruiter (a fee) increase. The client and candidate are both essentially 'buyers' in the sense that they have to agree to accept the other, and the recruiter is 'selling' to both parties.
But nobody wants to buy from someone who sells too hard, and that's what most recruiters end up doing.
When I started in recruiting, I wanted to be involved in every stage of the process to be sure I had some level of control. More recently I've realized that if the candidate is mature (and not going to make rookie mistakes like asking 3x market rate for salary just to 'test the waters') and the client has a decent hiring process, I'll make the intro and then step away until (if) I'm needed.
A recruiter can be quite helpful as a sounding board for both sides during negotiations to help facilitate a deal or save a deal that is failing.
>I’ve had folks change their mind even after accepting an offer. Hell, to be honest I’ve done it myself (and felt terrible about it).
A recruiter should also be helpful in providing guidance on situations like these. For example, I usually offer my clients a handful of tips to try and guarantee that someone who accepts the job will actually show up on day one. Having lunch with the new team between acceptance and start date is probably the most common.
But today's recruiter is far too interested in control. Make the intro, step away, and step in when necessary - otherwise, let them talk.