A good degree of decentralization is needed at the base layer. For second layers and end applications, the degree of decentralization can vary depending on what they are trying to accomplish. Total centralization is acceptable at those levels if at least account ownership, asset ownership, and transactions are assured by the base layer. If that is done at (virtually) no cost as it happens on Hive, it's much better than if operations on the base layer are expensive because that would force end apps and second layers to batch transactions together for lower fees and the user has to trust those layers' security or good intentions (in case of owners of centralized apps).
When it comes to social media, I believe total decentralization is not possible. That's why on Hive you have the right to post anything you want, but interfaces also have the right to not show harmful content if things get out of hand (I'm not aware of this being exerted so far on Hive, interfaces leave it to the community so far). In between comes the community with its downvotes, and various types of muting, which is a more decentralized way of hiding harmful content.