You can postulate cause and effect here, but the fact is that Sigur Ros are every bit as unusual and singular as their leader.
Sigur Ros (it means "Victory Rose") are the experimental/ ambient/progressive band (delete according to taste) whose songs are, like those of The Cocteau Twins or Cranes, often sung in an invented tongue, in this case Hopelandic (or Vonlenska). Which renders singalongs difficult, but it doesn't stop their fans, many of them shoeless in tribute to Jonsi's own fondness for removing his footwear onstage, from trying.
The devotion Sigur Ros inspire is a touching, and bewildering thing. SR do not believe in the cult of personality: wearing unadorned brown T-shirts, they are static for most of the show, and for much of it, one might as well be listening to a CD... although singer-guitarist Birgisson and bassist Georg Holm do play their instruments with a violin bow and drumstick respectively, and at one point the former lifts his guitar towards his teeth, and you think he's about to do a Hendrix. What he does is perhaps even more peculiar: he sings into the pick-ups with his high, keening voice (an impressive instrument in itself).
Devoid of intelligible lyrics, Sigur Ros's music is purest melody, and it's often fragile, delicate stuff, constructed with xylophones, marshmallow drumsticks, and soft Yamaha washes from Kjartan Sveinsson. You feel guilty for so much as rustling a crisp packet. There's a comical moment during "Svefn-G-Englar" when the courtyard bells toll the quarter hour and, intertwining with the glockenspiel, it could credibly be part of the song.
Every now and then, when the heavenly choirs soar and the orchestral sounds surge forth, you begin to understand why SR are so loved. There's also something oddly reassuring about a band as challenging as Sigur Ros being able to command a large-ish following.