If Google's a monopoly, who is harmed by its market power?

Google has long defended itself against charges of monopoly by stressing that its products are free and that no one has to use them.

And it's avoided tough government scrutiny for years based in part on the idea that people searching the internet are not Google’s true customers.

We’re its product. Advertisers are its real customers. That complicates the question of who, if anyone, is hurt by Google's dominance in selling ads off the world's search queries and through its array of affiliated businesses, from its Android phone software to its YouTube video platform and digital maps.

The U.S. Justice Department's new antitrust lawsuit against Google argues that both advertisers and regular people are harmed by the tech giant's position as “the unchallenged gateway to the internet for billions of users worldwide."

“As a consequence, countless advertisers must pay a toll to Google’s search advertising and general search text advertising monopolies," the government wrote in Tuesday's landmark complaint, which asks a federal court to intervene to protect competition. “American consumers are forced to accept Google’s policies, privacy practices, and use of personal data; and new companies with innovative business models cannot emerge from Google’s long shadow.”

The government argues that Google has abused its monopoly power through agreements with other companies that promote Google's apps and place its “search access points” as a default on browsers, phones and other devices. All of this drives more searches of Google at the expense of its rivals, the complaint alleges.

Google's critics have been making similar arguments for years in calls to break up the tech giant or curtail its behavior, but U.S. antitrust enforcers have long relied on a traditional standard of judging a monopoly by whether it's...