Clients usually request that their agents to work with a certain specific insurance company. This makes it easier for clients to compare various insurance policies and their quotes and to find the best plan for them, especially when a captive agent works for a large insurance company and is not as familiar with smaller companies and their policies.
Although both insurance agents and insurance brokers are intermediaries between prospective insurance buyers and insurance providers, the former act more like a broker and the latter act more like an insurance agent.