GREG IP: The Antitrust Case Against Facebook, Google, Amazon and Apple.

Standard Oil and Co. and American Telephone and Telegraph Co. were the technological titans of their day, commanding more than 80% of their markets.

Today’s tech giants are just as dominant: In the U.S., Alphabet Inc.’s Google drives 89% of internet search; 95% of young adults on the internet use a Facebook Inc. product; and Amazon.com Inc. now accounts for 75% of electronic book sales. Those firms that aren’t monopolists are duopolists: Google and Facebook absorbed 63% of online ad spending last year; Google and Apple Inc. provide 99% of mobile phone operating systems; while Apple and Microsoft Corp. supply 95% of desktop operating systems.

A growing number of critics think these tech giants need to be broken up or regulated as Standard Oil and AT&T once were. Their alleged sins run the gamut from disseminating fake news and fostering addiction to laying waste to small towns’ shopping districts. But antitrust regulators have a narrow test: Does their size leave consumers worse off?

By that standard, there isn’t a clear case for going after big tech—at least for now. They are driving down prices and rolling out new and often improved products and services every week.

That may not be true in the future: if market dominance means fewer competitors and less innovation, consumers will be worse off than if those companies had been restrained.

I’m wary of antitrust, particularly in the cases of Amazon and Apple. Retailers and gadgetmakers don’t enjoy nearly as much “stickiness” with consumers as social networking and search providers. Facebook and Google on the other hand, enjoy unprecedented access to the most intimate details of unprecedented numbers of consumers.

And those consumers are of course actually their (often unwitting) products.