Well the thing with printing is that the K part of CMYK is actually not the darkest black, yet it's 100% K that's used to print a book.
Fully saturated rich black (100% C+M+Y+K) is usually a little too jarring against a bright stock — take a look at most high quality books and notice that the stock is off-white and the ink isn't nearly as rich as #000 black on screen.
I think the original point as a lot of merit. Staying even just a little bit further from #000 or even pure grays (try #335, etc) can give more even tones and keep contrast high while reducing fatigue.
You're right about comparing art to print though — different goals, even though the conclusion is valid.
Fully saturated rich black (100% C+M+Y+K) is usually a little too jarring against a bright stock — take a look at most high quality books and notice that the stock is off-white and the ink isn't nearly as rich as #000 black on screen.
I think the original point as a lot of merit. Staying even just a little bit further from #000 or even pure grays (try #335, etc) can give more even tones and keep contrast high while reducing fatigue.
You're right about comparing art to print though — different goals, even though the conclusion is valid.