Ordinary human beings do not have the capital or the agility to simply change their business model overnight. If they did then Google would not have a monopoly in this sector. In the hypothetical world that exists solely for your argument yes, they could just go out and do something else the next day. In the actual world thousands of individuals and businesses are trapped by the real-world stranglehold that Google has on this sector, their monopoly. In absolute terms there are no monopolies. In the 1870's to the 1900's there was nothing stopping people from going out and drilling their own oil wells, opening their own steel mills and building their own railroads, but somehow the Rockefellers and the Vanderbilts of the world held on to their monopolies.
The only growth sector in advertising is monopolized by Google.
Keyword arbitrage is not wholly a parasite in this market, it does help to set values. While I personally avoid it, it exists because there is imperfect information in the marketplace. A greater number of players would help, but since there is a monopoly Google can regulate and learn from it by direct action as it did with Mr. Savage.
A monopoly deals with these things in a way that appears more unfair than if the marketplace simply drove Mr. Savage out of the business.
edited for factual, historical clarity
[edited by: OnlyToday at 1:53 pm (utc) on Sep. 16, 2008]