I did not know that. Thanks for the information and detailed explanation in the post. 3SPeak FAQ section still says this though:

Our system uses blockchain to store the content, meaning it cannot be arbitrarily removed.

Using the same logic, we probably can't say Steem is decentralized either since images are also not stored in the blockchain. Hypothetically speaking, if the storage providers or Steemit Inc delete all the Steem images that would break most of the Steem blog content.