Comment by echelon

> All your examples have replaced some other service in the past.

This was pre-broadband penetration, pre-smartphone. That was a really different era.

Social networking wasn't really that big before Facebook. Friendster, MySpace, and Xanga were all niche communities.

> Except GitHub, maybe.

Github toppled SourceForge, which was awful.

Reddit is probably the player that unseated the closest peer competitor. It toppled Digg, which was pretty big at the time. (Digg had itself disrupted Slashdot, StumbleUpon, and Del.icio.us, but those were niche communities.)