You are absolutely right. They are used everywhere in the Linux, OpenBSD, and FreeBSD kernels, and likely many other kernels. Replacing large linked lists with

You are absolutely right. They are used everywhere in the Linux, OpenBSD, and FreeBSD kernels, and likely many other kernels. Replacing large linked lists with arrays is rarely an actual win. With an array, insertion and deletion become far more expensive, virtual memory is more likely to become fragmented or grow monotonically, and the cache misses avoided are almost certainly irrelevant to total performance.