Earlier quoted context omitted.
Does anyone else have issues with identifying and describing facial features. I have no problems recognizing people, but there’s no way I can verbalize them on a specific features basis. What kind of disorder do I have?
Perhaps the artists are trained to ask questions of witnesses that reveal details you wouldn't be able to give up unprompted?
Draw a nose, was the bridge wider or thiner? With a lot of experience they seem to be able to get the "right" details close-enough that it can identify say, a large handful of people for whom those that might report them can feel more confident in say, calling the FBI before reporting their uncle.
This casts a wider net than say, directly identifying them, but it helps isolate the possible suspects well enough to be worth doing when you've got nothing else.