You are mistaken. The Steem blockchain has never been hacked. Some accounts where hacked on the steemit.com website (not the blockchain) last year in July (i think) and some funds were stolen. The exploit was patched and steemit.com covered the losses.
Do not confuse an application that runs on top of the blockchain with the blockchain. It's like saying that the latest exploit on the Jaxx wallet proves that Bitcoin was hacked.