I think what they mean by the "world" is the U.S.
2013 Glastonbury: 135,000 [0]
SXSW (music): 82,119 [1]
Neither of which compare to anything on this list[2]:
10th EXIT (NOVI SAD, SERBIA): 200,000
1st DONAUINSELFEST (VIENNA, AUSTRIA): 3,200,000
[0] http://en.wikipedia.org/wiki/Glastonbury_Festival [1] http://en.wikipedia.org/wiki/South_by_Southwest [2] http://www.mtviggy.com/lists/the-10-biggest-music-festivals-...
So even in the US SXSW is completely dwarfed by Coachella and Summerfest.
I think what they mean by the "world" is the U.S.