UC Supplemental information

Hi everybody, I know this has been discussed before, but I haven’t read anywhere of somebody being requested of them from all three schools that offer them: UC Berkeley, UCLA, and UCSD. What does this mean? I go to Arcadia High School, a very prestigious school, but I haven’t heard of anybody else at my school receiving this request from any of these three schools. I have a 3.68 unweighted gpa, I’ve taken 5 AP’s, I am one of the section leaders of a nationally ranked percussion ensemble, I was team captain of the water polo team, captain of the throwers on the varsity track and field team, and I got a 30 on the ACT. 35 in english, 32 in math, and 27s in reading and science. Somebody please help me to understand why all three schools want more information than what was given in the UC Application.