First of all, there isn't any consensus on how speakers are supposed to measure, and in any case they don't measure well.
Considering three primary measurements as: (1) absence of nonlinear distortion (2) frequency response and (3) directionality (which is a function of frequency), all practical speakers fail to be sonically ideal or even close to ideal.
Speakers suffer from high levels of nonlinear distortion at various points of their normal operating frequency response and SPL levels. Their frequency response in any direction (on-axis or off) fails to be flat and in any case does not approach any ideal contour.
As if that wasn't bad enough, there is no consensus on how directionality should be handled in the speaker realm. Any sort of theoretical "best compromise" in this element has been impractical to implement.
As a rule, speakers are so far from ideal that they are completely unmanageable if transparency is the main objective.
But I Do love speakers.