36MP lets you print Super B (13"x19") at 360DPI off one shot with a border. That is a significant step.
360DPI is just a number. Comparing visual end-results (like Erik tries) is more relevant than comparing numbers, I think.
360dpi (and up) is about the detail density that a person can get very close to an image with it still looking sharp. That gives an impression of quality to the buyer. Most people would not buy a larger blocky image. Even if you are supposed to step back to take it all in, people feel reassured in the quality when detail is there as far as they can see it.
"360dpi" and "36MP" are still only numbers. Numbers with somewhat vague definitions and implications for subjective impressions. Hands-on inspection beats numbers any time.
Subjective sharpness is (at least) affected by:
-Postprocessing (esp sharpening)
-Camera anti-aliasing filter