Net neutrality rules would keep broadband lines neutral of the Internet providers’ business interests. Say, for instance, you get high-speed Internet service from Comcast. Without strong rules, advocates say, Comcast could favor certain websites or videos on the lines coming into your home — perhaps those from TV networks it owns, or from outside companies from which it has exacted a fee for access to a special “fast lane” on the Internet.

Image Companies like Netflix and Kickstarter have supported net neutrality efforts. Credit... J. Emilio Flores for The New York Times

If that were to happen, proponents of the rules say, it’s obvious which companies would suffer most: the Internet’s newest and least powerful businesses. The giants, meanwhile, would escape relatively unscathed.

“If you have bad rules, the ones who pay the price are the smallest companies,” said Julie Samuels, the executive director of Engine, a group that has been pushing for network neutrality rules. “Once you’re as large as Google or Facebook, you can afford to pay.”

For much of the year, that dynamic has been playing out. Last September, web companies in favor of net neutrality supported an effort to slow down many well-known sites in order to demonstrate how web users would be harmed if net neutrality rules were not enacted.

“Our campaign was driven by a tight consortium of mostly New York City-based companies,” said Yancey Strickler, the chief executive and co-founder of Kickstarter, which took part in the effort, joined by Etsy, Tumblr, Vimeo and Netflix, among other upstarts.

But the Internet’s biggest names — Google, Facebook, Twitter, Microsoft, Amazon and Apple — sat out the protest. If you pulled up Google’s search results or Facebook’s News Feed on Internet Slowdown Day, you would not have noticed anything amiss.