Dedicating cores to specific server tasks is normal in modern high-performance software architectures. It can very substantially improve throughput of the system. For server code generally, and data intensive software specifically, there is a reasonable and valuable presumption that your hardware resources are dedicated to your task. This assumption greatly simplifies the design of high-performance software and tends to match the deployment environment of performance-sensitive software in any case.

Many high-performance software applications are constrained by network/disk bandwidth, so you would have cores doing no productive work regardless. This allows you to re-deploy those unused cores in other creative and useful ways. Specialization of cores has the added benefit of minimizing lock contention and making it simpler to reason about complex interactions between threads.