Are you....
A smart phone screen, displaying facebook specifically?
I probably won't blind you, but it certainly won't be pleasant
checking your screen at night isn't literally blinding, but quite unpleasant, especially with the facebook color scheme
The merger of a leader and global mass supporters
A smart phone could connect a public figure with all of their followers through social media, especially through facebook
Oft followed doubly by a joint and a set of ten
Hitting the "follow" button on the screen by moving some joint in your body, with your ten fingers "following" as in being next to or behind, the screen. The phone's screen can also be referred to as its face, and "facial features" could be a nice hint towards additional facebook "features" or functions other than following.