Isn't that what we're saying?

I figure that a limited amount of magical ability is natural in the FFVIII world. Perhaps some lingering remnant of Hyne's powers?

Sorceresses simply have more powerful, more diverse forms of magic at their disposal.

A few 'normal' people - Seifer, Quistis, Selphie, etc - have certain magical powers, and anybody can be given similar abilities by using junctions, or whatever it is that Galbadia's and Esthar's soldiers use.