Distribute load around the world, when if you're not a massively large site like Facebook you will only have one, maybe two points of presence. Protect you from DDoS attacks if someone decides they don't like you. As long as you set proper caching rules for ALL your static content (keyword: ALL), there is a decent chance that your bandwidth usage will drop in half or more... the list goes on.
I can't comment on this particular test as the page is down (Guess probably they should be using a proxy service or CDN...), but if it's anything like the previous report of Cloudflare slowness, it was light on science and high on personal thoughts.
Edit: It appears that this page was using a shared hosting provider called Netfirms? Probably shouldn't do that and then post to HN front-page...