(Matt Rourke/AP)

In the 2016 election, as special counsel Robert S. Mueller III’s probe and news reports have documented, Russian “troll farms” masqueraded as concerned Americans and used basic social media advertising and outreach to discourage potential Hillary Clinton voters and sway undecideds to Donald Trump. Any state-sponsored effort to interfere with U.S. elections is alarming, and lawmakers should protect against future intrusions. But the money spent by Russian operatives — only $100,000 on Facebook, for example — was a tiny fraction of the millions both presidential candidates spent on digital advertising. A new article in Wired carries far scarier information about digital political advertising and how the lack of regulation has directly hurt online debate.

In the article, Antonio García Martínez, who helped launch Facebook’s precision ad targeting in 2012, describes how Facebook auctions off the precious ad space in users’ feeds:

Facebook uses a complex model that considers both the dollar value of each bid as well as how good a piece of clickbait (or view-bait, or comment-bait) the corresponding ad is….A canny marketer with really engaging (or outraging) content can goose their effective purchasing power….Because Trump used provocative content to stoke social media buzz, and he was better able to drive likes, comments, and shares than Clinton, his bids received a boost from Facebook’s click model, effectively winning him more media for less money. In essence, Clinton was paying Manhattan prices for the square footage on your smartphone’s screen, while Trump was paying Detroit prices.

Different rates for different kinds of political ads are not unusual. The price of a TV ad depends on a number of factors, including location, time of day, whether the ad is purchased by the campaign or an outside organization such as a super PAC. What’s unheard of is “clickbait” being a criteria for an ad rate. And notice that there’s nothing in Facebook’s model (at least as Martínez describes it) that balances the clickbaitiness with whether the ad is misleading or not. So when the Trump team and its allies made more ridiculous ads that played on users’ fears, they got rewarded for it — incentivizing cheap propaganda over rational democratic discourse.

Furthermore, in other forms of advertising federal law has several requirements that level the playing field for federal candidates. TV stations, for example, must give federal candidates “equal opportunity” — that is, if they sell time to one candidate, they must make a similar amount of time available to other candidates. In the last several weeks of both primary and general elections (by far the most effective time for political ads), stations are also required to sell ad time to campaigns at the “lowest unit rate” — i.e., the lowest they’d charge advertisers for that time period — which means all campaigns are paying the same price during the most crucial period. Yet in the increasingly important category of digital advertising, Trump was able to get a leg up on Clinton in competing for the same demographics right up until Election Day.

Again, Russia using social media to sow dissent is disturbing, and everything should be done to protect against that threat. Sens. Amy Klobuchar (D-Minn.), Mark Warner (D-Va.) and John McCain (R-Ariz.) are sponsoring legislation that would create disclosure rules for online ads equal to those for TV and radio advertising, including who paid for the ad and whether it was endorsed by a candidate. That would be a good first step. But as Martinez writes, “the trail of blame often leads much closer to home.”

What’s needed is the political will for stronger regulations. When NBC’s Chuck Todd asked Klobuchar on Sunday whether Facebook and Twitter should be fined for failing to police their users, Klobuchar replied, “I think that would be a great idea, but then you need a Congress to act, and there are too many people who are afraid of doing something about this.” It won’t be easy: Digital titans such as Facebook and Google (and yes, Amazon, whose chief executive, Jeffrey P. Bezos owns The Post) spend millions to lobby Capitol Hill, and won’t take kindly to new laws. But what’s good enough for television and radio, once revolutionary communication methods, should be good enough for their modern successors. Inaction means our political debates are guaranteed to be further corrupted.