[thaumasiotes]

> Blue has best contrast on both white and black backgrounds, and stands out from black.

Why would it matter if it has good contrast on two different backgrounds? If you're changing the color of the background, you can also change the color of the link.

[al_borland]

It’s nice to be able to change between the two most common background colors without needing to develop a whole theme.

In the days before CSS was commonplace, it would also be very annoying to manage.