To begin with it’s value noting there appears to be some disagreement on this on the time of writing (February 2024).

instagibbs said in his coverage zoo doc:

There are N motivations for coverage that I do know of:

Anti-DoS: Solely “low-cost” issues to validate get flooded to the community

Safety: Sure forms of transactions could mess up sure programs for no good purpose

Improve hooks: We depart some issues “forbidden” such that if we discover a use for them later we don’t “confiscate” funds by refusing to relay e.g., a spend or pre-signed transaction

Professional-decentralization: Make it easy/low-cost for miners to construct blocks that pay properly

Paternalism: We would like pockets authors to make use of the least quantity of public assets whereas nonetheless undertaking their finish objectives(so long as that aim isn’t “assault the community”!).

Protected soft-fork course of: Generally the one mechanism stopping an unupgraded miner from mining a block that may be thought-about invalid by upgraded miners (however legitimate by unupgraded miners) is coverage discouragement.

Let folks pay charges to make transactions in a suitable API

All of those motivations clearly should be weighed in opposition to the truth that bitcoiners need to make transactions, and miners need charges from these transactions. Ideally we make a mempool/relay system the place each can reside in relative concord.

This corresponds to 2 of Suhas’ supposed functions in his Stack Change publish.

The aim of coverage checks is mostly to (a) shut off DoS vectors and (b) to make future consensus modifications safer to deploy, by stopping relay of transactions that may violate such future consensus modifications properly prematurely.

Gloria Zhao talks in regards to the trade-off between defending the bitcoind person from assaults (e.g. CPU exhaustion) and maximizing the reliability of charge bumping for L2 protocols in her presentation on “Transaction Relay Coverage for L2 Builders” at Adopting Bitcoin 2021.

These views to this point appear comparatively aligned though could embrace slight variations in prioritization.

A stronger disagreement is with those that suppose coverage is and must be used as a instrument to limit the propagation of sure use circumstances (ordinals, inscriptions and many others) even when these transactions are consensus legitimate and have a excessive charge fee. As well as Luke Dashjr takes the view (on X) that:

“Transaction pinning” AFAIK is a results of coverage centralization efforts, not an actual drawback. The choice is to encourage numerous insurance policies, and on the technical degree, to organize a number of different transaction variants to make sure one being rejected will not be an issue.

This alludes to a unique disagreement on whether or not default (mempool) coverage must be standardized throughout full node implementations to try to attain its supposed functions. Full node operators are at all times free to vary from the defaults (coverage will not be consensus) however standardization on this case would imply constant defaults throughout completely different implementations.