A look at OP_RETURN and whether embedding arbitrary data into Bitcoin's blockchain is spam

Bitcoin’s role as a data repository is often a topic of debate for many in the space. In the past, Bitcoin community members have argued the benefits of allowing arbitrary data unassociated with bitcoin transactions to be embedded into Bitcoin’s blockchain.

On one side of the debate, we have those that claim that as long as embedded data is paid for with transaction fees, any data should be accepted into the blockchain. On the other side, we have the purists who believe Bitcoin’s blockchain should only contain data necessary to validate bitcoin transactions and nothing else. Their argument stems from concerns of blockchain bloat. That is to say, because each node on the Bitcoin blockchain has to maintain and reference unspent transaction outputs (UTXOs) sets, excess data produced by these arbitrary data points would create upward pressure on the size of the blockchain — increasing the rate at which it grows.¹