When we say we don't use databases that's not just to say blockchain is more efficient. Actually, blockchain is incredibly more complex and difficult to develop apps on because of the layer of security and capability of smart contacts. By developing on-chain we allow users to remain in control of their data. This is the crucial element of web3 and building on-chain. Users can be trustless in their engagement with web3 apps, without fear of being compromised or taken advantage of.