It does not require a centralized server or service. It uses IPFS to achieve peer-to-peer content distribution. Furthermore, you can link your content to an Ethereum Name (.eth) so that others can follow you via Planet by the .eth name. Since both IPFS and ENS are decentralized, you can build your websites or follow others, all in a decentralized manner.
Good. I don't see anything wrong with this and it looks perfectly fine as a legitimate use case for a blockchain.