The debate surrounding the Bitcoin Core Pull Request (PR) to remove size limits on OP_RETURN, centers on how Bitcoin should balance its role as a financial system versus a platform for storing arbitrary data.
OP_RETURN is a Bitcoin script opcode that allows small amounts of data (currently capped at 80 bytes) to be embedded in transactions, often used for things like timestamps, notes, or metadata for sidechains and bridges. The proposal to lift this limit has sparked a heated discussion, with two distinct sides emerging: those against the change (Concept NACK) and those in favor (Concept ACK). Let’s break down their arguments in detail.
🔴 Side Against Removing Limits (Concept NACK)
This group opposes the proposal to remove OP_RETURN size limits, arguing that it undermines Bitcoin’s core purpose and introduces significant risks to the network’s efficiency and integrity. Here are their main points:
1. Increased Spam and Non-Monetary Use:
- Critics like Seccour, chrisguida, and wizkid057 (as cited in the thread) argue that removing OP_RETURN limits would invite more spam and non-financial data onto the blockchain. They see Bitcoin primarily as a monetary system, not a general-purpose data storage platform. For example, chrisguida warns that this change could turn Bitcoin into a “self-fulfilling prophecy” where it becomes a dumping ground for non-monetary data, similar to what some critics argue has happened with Ethereum.
- Historical precedent supports their concern: during the 2014 OP_RETURN Wars (mentioned in web ID 0 and web ID 3), projects like Veriblock used OP_RETURN to embed large amounts of data, leading developers to reduce the limit from 80 bytes to 40 bytes to curb spam before later raising it back to 80 bytes.
2. Crowding Out Financial Transactions:
- Opponents argue that allowing larger OP_RETURN data could clog the blockchain, increasing competition for block space and potentially crowding out legitimate financial transactions. Wizkid057 emphasizes that Bitcoin’s design prioritizes monetary use, and loosening limits could lead to “inevitable” abuse, where the blockchain becomes a “cheap place for people to dump their garbage forever.”
3. Impact on Network Efficiency:
- More data in transactions increases the burden on nodes, which have to store and relay this information indefinitely. Critics highlight that this could exacerbate issues like mempool congestion, where the pool of unconfirmed transactions grows, slowing down the network. Web ID 2 notes past congestion events, like in May 2023, when Ordinals and Inscriptions (which also embed data in transactions) caused Binance to suspend Bitcoin withdrawals due to network strain.
4. Preserving Node Sovereignty:
- The current limits allow node operators to configure settings like `-datacarrier` and `-datacarriersize`, giving them control over what data their nodes relay. Seccour argues that removing these limits takes away this sovereignty, forcing nodes to accept larger data payloads and reducing their ability to filter out spam. This is seen as a step toward centralization, as smaller nodes with limited resources might struggle to keep up.
5. Philosophical Concerns:
- Critics like Luke Dashjr (mentioned in web ID 2) call the proposal “utter insanity,” arguing that it accelerates the degradation of Bitcoin’s financial-first purpose. They fear Bitcoin could devolve into a “worthless altcoin” (web ID 0) if it prioritizes non-monetary use cases over its role as a sovereign monetary protocol.
🟢 Side For Removing Limits (Concept ACK)
Supporters of the proposal, including developers like Pieter Wuille, Sjors Provoost (web ID 2), murchandamus, and eragmus (from the thread), argue that removing OP_RETURN limits is a pragmatic and less harmful way to accommodate inevitable data storage on Bitcoin. Their key arguments are:
1. Data Storage is Inevitable:
- Proponents like eragmus argue that people will store data on Bitcoin regardless of restrictions, often using more harmful methods like embedding data in Taproot transactions (e.g., Ordinals and Inscriptions) or through private deals with miners. These alternatives can bloat the UTXO set (unspent transaction outputs), which slows down the network, as noted in web ID 2. OP_RETURN, by contrast, is provably unspendable, meaning it doesn’t contribute to UTXO bloat, making it a cleaner option.
2. Reducing Harmful Workarounds:
- Murchandamus points out that strict OP_RETURN limits push users to worse alternatives, like embedding data in ways that increase node traffic or encourage miner centralization (e.g., by negotiating directly with miners to include data). Relaxing the limits could guide data usage toward OP_RETURN, which is transparent and less disruptive. Web ID 2 highlights that this could also reduce mempool fragmentation, where the pool of unconfirmed transactions becomes inefficient due to cluttered data.
3. Encouraging Network Usage:
- Supporters like Karbon (web ID 0) argue that allowing more data via OP_RETURN can benefit the network by supporting applications like sidechains and bridges, which drive more transactions and increase Bitcoin’s utility. This aligns with a free-market perspective, where increased usage could lead to higher fees, potentially pricing out low-value data over time.
4. Aligning with Reality:
- Eragmus calls the change a “common-sense” adjustment, noting that Bitcoin Core’s restrictive stance on OP_RETURN doesn’t stop data embedding—it just pushes it into less desirable forms. They argue that by acknowledging and accommodating this reality, Bitcoin Core can better manage how data interacts with the blockchain, rather than fighting a losing battle against it.
5. Philosophical Support for Flexibility:
- Proponents believe Bitcoin should evolve to meet user demands while maintaining its core principles. They argue that OP_RETURN, being a small and unspendable part of a transaction, is a minimal concession that doesn’t fundamentally alter Bitcoin’s monetary focus. Murchandamus even suggests that larger OP_RETURNs could reduce mining centralization by decreasing the incentive for miners to prioritize private data deals over standard transactions.
Broader Context and Implications
The debate reflects a deeper tension in Bitcoin’s community between “purists,” who want to keep Bitcoin focused on its monetary purpose, and “pragmatists,” who see value in adapting to new use cases. Historical events like the 2014 OP_RETURN Wars (web ID 0, web ID 3) and the rise of Ordinals in 2023 (web ID 2) show that this isn’t a new issue—Bitcoin has long grappled with how to handle non-financial data. The NACK side prioritizes efficiency, sovereignty, and Bitcoin’s original vision, while the ACK side emphasizes pragmatism, harm reduction, and network growth.
Would you NACK or ACK this? The response from BillyBoone32 leans toward ossification (doing nothing), suggesting that market forces—like rising fees from economically valuable transactions—could naturally price out spam over time. This middle-ground view highlights the complexity of the issue, as both sides present compelling arguments rooted in Bitcoin’s technical and philosophical foundations.
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