I saw some the features of Paragraph and liked that the newsletter creator could hide parts of the content that would be visible only for specific NFT owners. I remember seeing some interesting posts on Mirror mainly about Ethereum projects but I think now the Farcaster/Warpcast platform got more attention from that blockchain community. By the way, maybe Substack still appears to be more popular and if you wish to reach a broader audience it could attract normal people beyond crypto supporters.
RE: Dead Internet Theory and the Rise of Emma Horsedick