It is not that it is more suitable, it is that the bitcoin layer counterparty XCP is where NFTs started, before the term NFT existed. In fact Mastercoin which is now called Omni a token layer still used on bitcoin was an inspration for Vitalik to create ETH in the first place. Here is a quick overview of what a token on counterparty can do: https://twitter.com/johnvillarz/status/1311807300206841858?s=20