Such Awesome thoughts all (Bat, Beeg, Mike, Mike, Jim, Herb); I'm pretty certain there's no dogmatic right or wrong answer to the metaphor of "drawing vs. painting" as it relates to singing vs. singing with extra stuff.
Part of the issue may be EMOTIONAL SENSITIVITY. (I don't know)
A sensitive woman may sing or draw with superb excellence. Her lines (vocal or etched) may yield an exquisite excellence that is swiftly destroyed by robust distortion guitars and choirs.
Likewise, sensitive melodic Eastern artists (Chinese, etc.) don't oft seem to fair well with expressionistic paintings, choirs and bands ... compared to Western bands. They can draw well ... with introspective excellence.
OTOH, robust expressionistic metal warriors may exploit distortions, rhythms, and such to sing/paint ... at least at some points in their canvases.
I wonder if Alice Cooper or Robert Plant could sing acapella without sounding plain (or ugly). Hahahaha! IMHO, Led Zep seemed to terminate when their drummer died.
... Western pop artists seem to thrive on bass and groove colorations to express themselves 'adequately'. I doubt many hip-hop singers could 'last-it' without beatz as part of their rant.
Then there are you guys! You guys all sing wonderfully; IMHO, JMO.
And, I know you can sing solo-acapella SOMEWHAT ... hahahaha! But many of you seem to richly paint song portraits better than you can draw them IYKWIM.
OTOH, Reece (to my ears) seems able to sweetly deliver both solo opera-antics ... AND rich colorful blues. So every talent here has diverse gifts that would probably violate my perceptions ... perhaps depending of genres and such.
I just 'observe' that my vox and those of many of you here 'currently' rivet well toward colorfully glazed mixes, duets, quartets, etc. ... despite years of faithful singing and song-leading.
I know I can paint a symphonic masterpiece but I can't seem to draw elegantly ... without multi-instruments or vocs harmonizing and such.