Unless you mean a layer 3 switch a managed switch usually provides port level configurations. Such as VLANs and QoS features to prioritize VOIP or other traffic. The router will still control the network and a decent SDN controller can inform the network without having to perform device level configs but I digress.

With a layer 3 switch you can avoid hops to the router and also get some hardware acceleration. Although the lines are increasingly blurred between switch and router with hardware acceleration becoming popular all around. Most consumer routers are router/switch combos.