When we talk static HTML I think that still includes images, stylesheets and potentially even very basic javascript (e.g. setting classes). Those take advantage of CDNs; Cloudflare have an extensive CDN with decent latency / locations. They also are a DNS registrar and a lot of people use them for their local DNS provider so again latency benefits. That's before we talk about the DDoS protection, injecting stuff like metrics etc etc. I don't want to sound like a Cloudflare rep here but I can see where this user is coming from.