Spacetimes are the arenas in which all physical events take place . . . an event is a point in spacetime specified by its time and place. For example, the motion of planets around the sun may be described in a particular type of spacetime, or the motion of light around a rotating star may be described in another type of spacetime. The basic elements of spacetime are events. In any given spacetime, an event is a unique position at a unique time."
[link to en.wikipedia.org (secure)]

See how the Einsteinians play slight of hand? Reference frames are now "Spacetime arenas." The ". . . motion of light around a rotating star may be described in another type of spacetime."

You see, Lorentz, Einstein, Voigt, et al try to describe the "motion of light" as a single point, transformed into various reference systems, which are now called "arenas."

Please note, from the above quote: "an event is a unique position at a unique time"

This definition means that an event cannot be an expanding sphere of light. An expanding sphere of light does not occupy a "unique position at a unique time." (i.e. a single point set of coordinates within a reference frame) The sphere is not a single point.