Aren't most of the colors we're talking about outside most (or all) monitor's gamuts?
Generally, yes.
Aren't many of the colors we're talking about outside any current printer's gamut?
I do want to avoid colors blocking up due to gamut compression. I do want to be sure that my RGB image will convert well to CMYK. Question: How does an "intelligent human operator" use this color data intelligently (in a way that leads to a better printed result)?
This appears to me to be an area (like monitor calibration) where I might prefer a well written piece of color management code to my eyes.