But they have built the perfect shim in the middle to do ALL of these things at some point in the future.
The only thing preventing it is a handful of moral executives, who someday will move on or retire. At that point a smart Wall Street type is going to figure out that a merger between CloudFlare and $adnetwork is going to generate a shit ton of money (think Google+DoubleClick).
I don't doubt that CloudFlare is full of smart well meaning people, but what they have built is a ticking timebomb. The solution is to have ten CloudFlares so that the path between consumers and websites isn't regulated by a single organization.
Edit: to be clear, the internet was successful because any host could talk to any other host. If people did dumb shit you could work around it in creative ways. Even in the most oppressive countries censorship is still bypassable. CloudFlare's business model is centered around convincing companies to effectively disconnect their services from the internet so they only talk to CF servers.