I don't get it either. I'd like to hear from a designer on why this ever happens. I used to work with a designer who set h2 to 11px. Boggles my mind. Does tiny type look better? I honestly don't get it.
there are a few reasons I can think of to use tiny type. For one, designers who are used to print might not understand that things should be bigger on the web, because you generally read websites at a further distance. Second, most fonts aren't designed for screens; and thus don't look good at larger sizes. 18pt for a font designed for body copy in print can be jarring sometimes. Lastly, and this might sound silly, but smaller type leaves more room for other stuff. Some people think scrolling is a pain.
