Twitter's canny political ad ban costs it little – and piles pressure on Facebook

Jack Dorsey has cut off a tiny revenue stream while focusing attention on rival's inaction

Twitter's announcement that it will ban all political advertising has prompted a wave of calls for Facebook to do the same. But Twitter's political advertising operation had just 21 advertisers across the entirety of the EU during the parliamentary elections this year, according to the site's transparency report.

The Twitter co-founder and chief executive, Jack Dorsey, has turned a weakness into a strength, cutting off a minuscule revenue stream in order to heap pressure on his main competitor. In the hours since Twitter's announcement, support has come from voices as diverse as the US-based campaign group Muslim Advocates, the Open Knowledge Foundation thinktank and the screenwriter Aaron Sorkin.