I think the question is more do you retain control over the content. Since it is written to a blockchain, I would say it depends on how the blockchain functions. If you can delete your content later, permanently, from the chain, then you do still own it. But if you can't, then I can't see how ownership means that much. If the blockchain itself is considered a common asset of humanity, your content is effectively public domain.

With bitcoin, ownership is being able to move bitcoin to a new address. However, that doesn't delete the record of where that bitcoin has been--that can never be deleted. So while you retain ownership, or at least control, of your bitcoin, you do not own the ledger itself. Is Steemit content part of the ledger or is it an asset you can move around? Although to be fair even moving bitcoin doesn't destroy it. It can never be destroyed, just made inaccessible. So perhaps nobody truly owns bitcoin, they just control it for awhile. These are interesting questions.