Recruiters generally go on keywords and years of experience to assess candidates while managers can go deeper into a candidate's knowledge and ideas. Continuous recruiting also helps managers to become better judges of what they need in a new hire and what is available in the market. By continually sourcing and building relationships managers build contacts that can lead to further learning and referrals. Recruiters also build networks but those seldom help us develop better products because the information is seldom passed on to those that can utilize it. Personal assessment and growth - Retaining managers is a major problem with most firms.
Lack of growth is a primary reason why managers quit, just like it is for employees.
In addition, candidates want to know and trust their future bosses. This extended relationship also improves the quality of the candidate assessment process because it allows for assessment to occur over a longer period of time. Recruiters can converse for a brief period with most technical people but no one ever takes a job based just on what a recruiter says. Recruiters do gain a great deal of knowledge and many I know become business experts. They know the latest trends, products, employee and customer expectations but that information is seldom passed on to decision makers.