J.M. Berger returns to the fray:
The Islamic State has found its latest social media flavor of the month, the encrypted and security-conscious messaging service known as Telegram.

(Then in a twist) So why do ISIS supporters keep returning to Twitter, Facebook and YouTube, despite the significant pressure from fast and furious suspensions?....The answer is simple. That’s where the audience is. While ISIS can and will seek out alternative platforms for its propaganda and recruitment efforts, it can’t make its targets come along for the ride.
Link:https://www.hate-speech.org/isis-and-the-big-three/