Google has 23,000 employees and ~$10B in yearly operating income. I'm pretty sure they could stay ahead of the bad guys if they wanted to.
EDIT: Additionally, it is hard to game pagerank rapidly because the rest of the web needs to link to your site. So, even if you switch your knock-off wikipedia site to a new domain, it would take weeks/months to rise through the rankings. I'm pretty sure it would only take a few employees (at most) to stay ahead of these huge spam sites.
Compared to how many millions of people making money on the web, all of whom have an incentive to boost their own traffic regardless of whether that's the best thing for users?
Joy's Law comes into play here: "No matter who you are, most of the smartest people work for someone else." 23,000 employees sounds huge, until you compare it with the million+ people who make their living as full-time E-bay sellers, and the however many million people who make their living off AdSense.
Google has 23,000 employees ... . I'm pretty sure they could stay ahead of the bad guys if they wanted to.
In the past there were people within Google who had the skill, knowledge, organizational connections and authority to quickly and gracefully reduce the problem of link spam without harming the bottom line too much.
I think we all loved their early work, and our love helped propel their little company to multibillions-per-year.
I don't think that kind of unique early experience and subsequent problem-solving effectiveness is snap-in interchangeable.
Some of those "rock stars" work at Facebook now. Google might not be capable of fixing the problem gracefully without them.
it is hard to game pagerank rapidly because the rest of the web needs to link to your site
Not really. Some people own different websites, purchased through different accounts, hosted on different servers. They, then, link between those sites.
EDIT: Additionally, it is hard to game pagerank rapidly because the rest of the web needs to link to your site. So, even if you switch your knock-off wikipedia site to a new domain, it would take weeks/months to rise through the rankings. I'm pretty sure it would only take a few employees (at most) to stay ahead of these huge spam sites.