Between 2014 and 2017, the Islamic State maintained vibrant communities on a range of social media platforms. Due to aggressive account and content takedown policies by the major platforms, these visible communities are now almost non-existent. Following the March 2019 Christchurch attack, the question as to why major platforms cannot rout the extreme right in the same way has repeatedly arisen. In this article, Maura Conway explores why this is not as straightforward as it may seem.