Many who buy on Coinbase never own Bitcoin. They deposit money, make some transactions, and perhaps pull out their fiat. If they don't see it touch the blockcha

Many who buy on Coinbase never own Bitcoin. They deposit money, make some transactions, and perhaps pull out their fiat. If they don't see it touch the blockchain, it's never Bitcoin, but little more than a row in a database that can presumably be exchanged for Bitcoin (which doesn't exist until it's sent to a BTC address) At the same time, those users don't care. As long as they feel confident that their account balance is valid and safe, the rest is just noise to them, regardless of how purists feel.