Privacy groups, the U.S. Federal Trade Commission, and some lawmakers have pushed do-not-track technology as a way for Web users to control who collects their personal information.

In May, FTC Chairman Jon Liebowitz the Internet industry to embrace do-not-track technologies. "A do-not-track mechanism should be implemented universally to cover all parties that would track consumers," he said then.

Over the long term, do-not-track could cause huge problems for Internet businesses, if browser users embrace the technology on a large scale, Castro wrote. "Website operators will see a substantial decrease in revenue," Castro said in his blog post. "A substantial decrease in revenue means a corresponding substantial decrease in free (or low-cost) content, apps and services. Or websites could try make up lost revenue by filling their websites with more untargeted ads."

Some websites may end up blocking users who have do-not-track enabled, just as some websites have put up pay walls to block nonpaying users. There are several plugins for blog platform WordPress that allows blog operators to block users who run ad-blocking software, he noted.

"Website owners will likely have similar tools if Do Not Track becomes widespread," Castro added. "It is my hope that with this alert ITIF will be able to remind people how easy it would be for sites to block users who enable Do Not Track, and by outlining how this will likely play out, policy makers will realize this is a useless endeavor."