That has always sounded like anecdotal evidence to me. Reading on a monitor should in that case be like reading paper in very good light, although with lower resolution. What is the qualitative difference between emitted light and reflected light?
I suppose reflected light matches better with the ambient, while with emitted light this is difficult to get. Matchng both, brightness and color.
Also, I don't like to read on white background (neither screen or paper), and on the computer nowadays the more usual background is white... I like yellowish backgrounds.