[berberous]

If everybody in the world agreed to only buy and sell digital art on OpenSea, then it is no different, assuming you trust OpenSea to operate fairly and to not lose records or make mistakes.

But practically, nobody has ever been able to convince the world to only buy and sell on one platform, and even if they could, that would be a worse solution because better platforms may emerge and it’s nice to have alternatives.

Stated another way, today, OpenSea could not possibly track all NFT transactions in a centralized database without just mirroring the data in the blockchain, as many transactions occur off platform.