Yesterday, Jack Dorsey made a bold statement: Twitter will cease all political advertising on the platform. “Internet political ads present entirely new challenges to civic discourse: machine learning-based optimization of messaging and micro-targeting, unchecked misleading information, and deep fakes. All at increasing velocity, sophistication, and overwhelming scale,” he tweeted.

Later that day, Sheryl Sandberg responded: Facebook doesn’t have to cease political advertising… because the platform is “focused and leading on transparency.” Sandberg cited Facebook’s ad archive efforts, which ostensibly allow researchers to study the provenance and impact of political ads.

To be clear: Facebook is still falling short on its transparency commitments. Further, even perfect transparency wouldn’t change the fact that Facebook is accepting payment to promote dangerous and untrue ads.

Some brief history: Because of the importance of transparency in the political ad arena, Mozilla has been closely analyzing Facebook’s ad archive for over a year, and assessing its ability to provide researchers and others with meaningful information.

In February, Mozilla and 37 civil society organizations urged Facebook to provide better transparency into political advertising on their platform. Then, in March, Mozilla and leading disinformation researchers laid out exactly what an effective ad transparency archive should look like.

But when Facebook finally released its ad transparency API in March, it was woefully ineffective. It met just two of experts’ five minimum guidelines. Further, a Mozilla researcher uncovered a long list of bugs and shortcomings that rendered the API nearly useless.

The New York Times agreed: “Ad Tool Facebook Built to Fight Disinformation Doesn’t Work as Advertised,” reads a July headline. The article continues: “The social network’s new ad library is so flawed, researchers say, that it is effectively useless as a way to track political messaging.”

Since that time, Mozilla has confirmed that Facebook has made small changes in the API’s functionality — but we still judge the tool to be fundamentally flawed for its intended purpose of providing transparency and a data source for rigorous research.

Rather than deceptively promoting their failed API, Facebook must heed researchers’ advice and commit to truly transparent political advertising. If they can’t get that right, maybe they shouldn’t be running political ads at all for the time being.