Yeah IIRC he has a page elsewhere listing system fonts and proposing alternatives, including several free fonts. I'm pretty sure the reason is just that free fo

Yeah IIRC he has a page elsewhere listing system fonts and proposing alternatives, including several free fonts. I'm pretty sure the reason is just that free fonts tend not to be "full featured." His typographic style is based on classic printing, so it really depends on the font having features like small caps, tabular, lining, & proportional number options, etc.