Schaaf first posted about Imgur on Digg, and when it didn't gain traction there he posted it on Reddit. It was disingenuous of him to call it a "Gift to Reddit" in that post.
imgur was the first image host (before minus) that didn't suck, wasn't anti-user, freely allowed hotlinking and had a minimal page when they didn't hotlink.
It's almost never down and the links don't magically fail or expire after they get lots of traffic like many other hosts.