If it's difficult, as opposed to unrealistic, then it's a good opportunity for a third party (or a google spin-off) to wholly dedicate itself to solving. Also,

If it's difficult, as opposed to unrealistic, then it's a good opportunity for a third party (or a google spin-off) to wholly dedicate itself to solving. Also, PageRank is easier to game because Google must stick to existing rules (eg: if it's on the web, Google is supposed to index it). When it comes to a service tied to a user account, the site operator has more agency to impose its own rules.