What about the distance too? Do you really stick the phone one foot from your nose to read it? I hold it nearly 1.5 to 2 feet (at LEAST) normally. My eyesight sucks too - so if I looked at something at a foot or less, I'd have to take my glasses off.
It's all marketing malarky (I worked in print, so perhaps that's a bias) but I can tell the difference between a 300dpi laser jet page, and a 1200dpi linotronic typeset piece of film. I'd call out SJ on the "eye can't see more than 300dpi" business than "the phone held at a certain angle, at a certain distance, preferably at noon, but not on a leap year, with a cat present in the room".