I do have one question:
How comes all of these groups that oppose or are against the U.S. keep using american social media to tweet or whatever?
Actually they have been branching out towards using alternative social media services:
In August 2014, Twitter administrators shut down a number of accounts associated with ISIL. ISIL recreated and publicised new accounts the next day, which were also shut down by Twitter administrators. The group has attempted to branch out into alternative social media sites, such as Quitter, Friendica and Diaspora; Quitter and Friendica, however, almost immediately worked to remove ISIL's presence from their sites.
Link:
http://en.wikipedia.org/wiki/Islamic_State_of_Iraq_and_the_Levant#Propaganda_and_social_mediaAs for why they prefer to use Twitter, it's probably because they are the most popular social media platform and therefore the most effective one. You wouldn't want to put your crowdfunding project on a site that nobody visits, for example.