I think the described machines were designed for a very specific workloads even in CDNs world. As I guess they serve exclusivelly fragments of on-demand videos, no dynamic content. So high bytes to number of requests ratio, nearly 100% hit ratio, very long cache TTL (probably without revalidation, almost no purge requests), small / easy to interpret requests, very effective HTTP keep alive, relatively small number of new TLS sessions (TLS handshake is not accelerated in hardware), low number of objects due to their size (much fewer stat()/open() calls that would block nginx process). Not talking about other CDN functionality like workers, WAF, page rules, rewrites, custom cache keys, no or very little logging of requests etc. That really simplifies things a lot compared to Cloudflare or Akamai.