Ask HN: Reason for the DDoS attacks on DALnet circa 2002?

Watching DALnet get almost completely destroyed by sustained DDoS attacks around 2002 was a formative memory for me, but I never did figure out why it happened, or what made DALnet more vulnerable than other IRC networks. Many of the simple explanations (warez? extortion? demo of botnet-for-hire?) don't really seem likely, and don't fit the facts.

Does anyone know what the story really was?