That’s just the way it is.

When Reddit was new, it mentioned Digg a lot.
When Digg was new, it mentioned /. a lot.
When /. was new (yes, I was there, too), it mentioned Usenet a lot.

At some points in time, the likes of The WELL, the Facepunch forums and Metafilter got their own mentions, prompting me to check them out.