Serifs are irrelevant, and browsers have had variable-width fonts since Mosaic, WorldWideWeb and ViolaWWW, so making textareas use a monospaced font and specify

Serifs are irrelevant, and browsers have had variable-width fonts since Mosaic, WorldWideWeb and ViolaWWW, so making textareas use a monospaced font and specifying their size like that seems to have been just laziness. If there was a good reason, I'd be interested to know it.